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Which Order Should Columns Go in an Index?: Finding All the Red Sweets Part 4
 
06:19
When you create an index on multiple columns there's an important question you need to answer: In which order should you list the columns? This video looks at some of the factors you should consider to help answer this question. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 4622 The Magic of SQL
07 04 Index Column Order Matters
 
04:53
ORACLE
Views: 108 oracle ocm
Index in SQL | Oracle SQL Tutorial Videos | Mr.Vijay Kumar
 
20:16
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Views: 43936 Naresh i Technologies
07 05 Demo   Index Column Order
 
03:59
ORACLE
Views: 61 oracle ocm
DBMS Indexing: The Basic Concept
 
09:52
A quick introduction to the concept of indexing in RDBMSs
Views: 177362 Brian Finnegan
Database Design 39 - Indexes (Clustered, Nonclustered, Composite Index)
 
13:28
This video covers the basics of indexes. Indexing is an extremely important step of database design. Without Indexes database queries can take a substantial amount of time and hog system resources. The main two classifications of indexes are clustered and non-clustered indexes. Clustered indexes are usually the primary key and determine how the data is actually stored in the table. These are the fastest and most effective. Non-clustered indexes sort a reference to data that is still fast but doesn't actually determine how the data is structured. The best tip I can give you is to use indexes but don't over use them. Having loads of indexes on columns that are barely ever in a where clause or join can bog down the database. This is because every time the table is updated the index must also be updated! When a database looks through a table for certain where conditions on a column that does not have an index, it does an entire table scan. This is not a good practice for large databases (or even small databases but not as bad). With an index the database will do an index seek and quickly find the data you are looking for. Composite indexes consist of two or more columns within one index. Use these when you plan on using the two columns together for a database query WHERE clause. Learn more about indexes here: https://www.calebcurry.com/blogs/database-design/introduction-to-indexes Donate!: http://bit.ly/DonateCTVM2. Courses for Download: http://www.udemy.com/u/calebcurry/ (Use the coupon code "YouTubeDiscount" without the quotes) Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Subscribe (it's free!): https://www.youtube.com/channel/UCZUyPT9DkJWmS_DzdOi7RIA?sub_confirmation=1 Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 103497 Caleb Curry
A Story of Indexes and Full Table Scans: Finding All the Red Sweets Part 1
 
08:43
"Why isn't Oracle using my index?!" is a common question people have when tuning SQL queries. In this episode Chris compares two methods for finding all the red candies from party bags he's prepared. He shows how these are like a full table scan and an index range scan. He goes on to compare the performance of these two approaches. He shows when a full table scan becomes more efficient than an index range scan and vice versa. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 8836 The Magic of SQL
09 02 What Should I Index
 
06:54
ORACLE
Views: 42 oracle ocm
Why Is My Query Slow? More Reasons Storing Dates as Numbers Is Bad
 
05:25
Storing dates as numbers can cause unexpected problems. In this video Chris looks at one possible issue: inconsistent query performance. He then shows methods you can use to improve performance, including function-based indexes and histograms. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 7692 The Magic of SQL
09 09 Index not Selective Enough
 
01:30
ORACLE
Views: 26 oracle ocm
PART 5.4 Types of Indexing in DBMS in HINDI different classification of indexing physical secondary
 
09:04
• Counselling Guruji is our latest product & a well-structured program that answers all your queries related to Career/GATE/NET/PSU’s/Private Sector etc. You can register for the program at: https://goo.gl/forms/ZmLB2XwoCIKppDh92 You can check out the brochure at: https://www.google.com/url?q=http://www.knowledgegate.in/guruji/counselling_guruji_brochure.pdf&sa=D&ust=1553069285684000&usg=AFQjCNFaTk4Pnid0XYyZoDTlAtDPUGcxNA • Link for the complete playlist of DBMS is: https://www.youtube.com/playlist?list=PLmXKhU9FNesR1rSES7oLdJaNFgmuj0SYV • Links for the books that we recommend for DBMS are: 1.Database System Concepts (Writer: Avi Silberschatz · Henry F.Korth · S. Sudarshan) (Publisher: McGraw Hill Education) https://amzn.to/2HoR6ta 2.Fundamentals of database systems (Writer:Ramez Elmsari,Shamkant B.Navathe) https://amzn.to/2EYEUh2 3.Database Management Systems (Writer: Raghu Ramkrishnan, JohannesGehrke) https://amzn.to/2EZGYph 4.Introduction to Database Management (Writer: Mark L. Gillenson, Paulraj Ponniah, Alex Kriegel, Boris M. Trukhnov, Allen G. Taylor, and Gavin Powell with Frank Miller.(Publisher: Wiley Pathways) https://amzn.to/2F0e20w • Check out our website http://www.knowledgegate.in/ • Please spare some time and fill this form so that we can know about you and what you think about us: https://goo.gl/forms/b5ffxRyEAsaoUatx2 • Your review/recommendation and some words can help validating our quality of content and work so Please do the following: - 1) Give us a 5-star review with comment on Google https://goo.gl/maps/sLgzMX5oUZ82 2) Follow our Facebook page and give us a 5-star review with comments https://www.facebook.com/pg/knowledgegate.in/reviews 3) Follow us on Instagram https://www.instagram.com/mail.knowledgegate/ 4) Follow us on Quora https://www.quora.com/profile/Sanchit-Jain-307 • Links for Hindi playlists of other Subjects are: TOC: https://www.youtube.com/playlist?list=PLmXKhU9FNesSdCsn6YQqu9DmXRMsYdZ2T OS: https://www.youtube.com/playlist?list=PLmXKhU9FNesSFvj6gASuWmQd23Ul5omtD Digital Electronics: https://www.youtube.com/playlist?list=PLmXKhU9FNesSfX1PVt4VGm-wbIKfemUWK Discrete Mathematics: Relations:https://www.youtube.com/playlist?list=PLmXKhU9FNesTpQNP_OpXN7WaPwGx7NWsq Graph Theory: https://www.youtube.com/playlist?list=PLmXKhU9FNesS7GpOddHDX3ZCl86_cwcIn Group Theory: https://www.youtube.com/playlist?list=PLmXKhU9FNesQrSgLxm6zx3XxH_M_8n3LA Proposition:https://www.youtube.com/playlist?list=PLmXKhU9FNesQxcibunbD82NTQMBKVUO1S Set Theory: https://www.youtube.com/playlist?list=PLmXKhU9FNesTSqP8hWDncxpCj8a4uzmu7 Data Structure: https://www.youtube.com/playlist?list=PLmXKhU9FNesRRy20Hjr2GuQ7Y6wevfsc5 Computer Networks: https://www.youtube.com/playlist?list=PLmXKhU9FNesSjFbXSZGF8JF_4LVwwofCd Algorithm: https://www.youtube.com/playlist?list=PLmXKhU9FNesQJ3rpOAFE6RTm-2u2diwKn • About this video: This video discusses the Types of Indexing in database in Hindi. Important topic of database Indexing like need of indexing in database management indexing, Why we do indexing in files in database, How we do indexing in dbms, Types of indexing, Methods of Indexing, Advantages of Indexing, How to access a file fast in database, Single level Indexing in database file, Multilevel indexing in database file structure in dbms, Primary Indexing in database, Clustered Indexing in database, Secondary Indexing file in dbms, Advantages of using single level Indexing in database are discussed. Single level index: This means we create index file for the main file, and then stop the process. Multiple level index: This means, we further index the index file and keep repeating the process until we get one block. Multi-level Index helps in breaking down the index into several smaller indices in order to make the outermost level so small that it can be saved in a single disk block-0, which can easily be accommodated anywhere in the main memory. A.) PRIMARY INDEXING- i)Main file is always sorted according to primary key. ii)Indexing is done on Primary Key, therefor called as primary indexing B.) CLUSTERED INDEXING: - i)Main file will be ordered on some non-key attributes ii)No of entries in the index file = no of unique values of the attribute on which indexing is done. iii)It is the example of Sparse as well as dense indexing C.) SECONDARY INDEXING- i)Most common scenarios, Suppose that we already have a primary indexing on primary key, but there are frequent query on some other attributes , so we may decide to have one more index file with some other attribute. ii)Main file is ordered according to the attribute on which indexing is done(unordered). iii)Secondary indexing can be done on key or non-key attribute. iii)It is an example of dense indexing. Indexing in dbms, Indexing in dbms tutorial in hindi,about indexing in dbms,indexing and hashing in dbms, terminologies in indexing in database,indexing in dbms example,indexing in dbms tutorial,disadvantages of indexing in dbms,indexing in dbms for gate,
Views: 125459 KNOWLEDGE GATE
14.503 Challenges in Query Optimization: Join Order, Costs, and Index Access
 
14:53
My book "Patterns in Data Management" is now available both as an ebook or a print book (with color graphics!). See: http://amzn.to/1Ts3rwx This book is not a standard textbook on database techniques. This book was written extending and complementing preexisting educational videos (including this one). Video for my inverted classroom "Database Systems". The complete list of videos, slides, and additional material is (will be) available at http://datenbankenlernen.de Computer Science, Saarland University: Bachelor (in German): http://www.cs.uni-saarland.de/index.p... Master (in English): http://www.cs.uni-saarland.de/index.p... Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/ -- Copyrights: © iStock.com: Rastan, moenez
B-Tree Indexes
 
04:33
In this video, I'd like to take a look at B-tree indexes and show how knowing them can help design better database tables and queries.
Oracle Hints Tutorial for improving performance with examples
 
11:16
Oracle Hints Tutorial for improving performance with examples Oracle Hints Oracle Tutorial for beginners SQL Tutorial for beginners SQL Hints SQL Performance tuning
Views: 4729 TechLake
Does The Order Of Index Columns Matter?
 
06:26
Have you ever wanted to create an index to improve SQL query performance but were unsure of what columns to include or what order to put them in? This video will explain everything you need to know to understand how SQL row store indexes work. Subscribe and turn on notifications to never miss a weekly video: https://www.youtube.com/c/bertwagner?sub_confirmation=1 Related blog post with examples and graphics: https://bertwagner.com/2018/09/04/does-the-order-of-index-columns-matter/ Follow me on Twitter: https://twitter.com/bertwagner
Views: 568 Bert Wagner
How Does the Phyiscal Location of Rows Affect Indexes?: Finding All the Red Sweets Part 2
 
09:25
In part one of the red candy series, Chris compared the efficiency of using a index range scan and full table scan to access data. He found that a full table scan was more efficient when fetching more rows than there are table blocks. This analysis made a big assumption however. It worked on the presumption that there was no correlation between the order of candies in the document and which the bags they were in. In this episode tests this assumption. Chris looks at how the physical order of rows in a table can affect the efficiency of indexes on it. He discusses how Oracle tracks this via the clustering factor. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 3485 The Magic of SQL
PART 5.3 Indexing in dbms in hindi basics of indexing in dbms primary secondary clustered
 
20:31
• Counselling Guruji is our latest product & a well-structured program that answers all your queries related to Career/GATE/NET/PSU’s/Private Sector etc. You can register for the program at: https://goo.gl/forms/ZmLB2XwoCIKppDh92 You can check out the brochure at: https://www.google.com/url?q=http://www.knowledgegate.in/guruji/counselling_guruji_brochure.pdf&sa=D&ust=1553069285684000&usg=AFQjCNFaTk4Pnid0XYyZoDTlAtDPUGcxNA • Link for the complete playlist of DBMS is: https://www.youtube.com/playlist?list=PLmXKhU9FNesR1rSES7oLdJaNFgmuj0SYV • Links for the books that we recommend for DBMS are: 1.Database System Concepts (Writer: Avi Silberschatz · Henry F.Korth · S. Sudarshan) (Publisher: McGraw Hill Education) https://amzn.to/2HoR6ta 2.Fundamentals of database systems (Writer:Ramez Elmsari,Shamkant B.Navathe) https://amzn.to/2EYEUh2 3.Database Management Systems (Writer: Raghu Ramkrishnan, JohannesGehrke) https://amzn.to/2EZGYph 4.Introduction to Database Management (Writer: Mark L. Gillenson, Paulraj Ponniah, Alex Kriegel, Boris M. Trukhnov, Allen G. Taylor, and Gavin Powell with Frank Miller.(Publisher: Wiley Pathways) https://amzn.to/2F0e20w • Check out our website http://www.knowledgegate.in/ • Please spare some time and fill this form so that we can know about you and what you think about us: https://goo.gl/forms/b5ffxRyEAsaoUatx2 • Your review/recommendation and some words can help validating our quality of content and work so Please do the following: - 1) Give us a 5-star review with comment on Google https://goo.gl/maps/sLgzMX5oUZ82 2) Follow our Facebook page and give us a 5-star review with comments https://www.facebook.com/pg/knowledgegate.in/reviews 3) Follow us on Instagram https://www.instagram.com/mail.knowledgegate/ 4) Follow us on Quora https://www.quora.com/profile/Sanchit-Jain-307 • Links for Hindi playlists of other Subjects are: TOC: https://www.youtube.com/playlist?list=PLmXKhU9FNesSdCsn6YQqu9DmXRMsYdZ2T OS: https://www.youtube.com/playlist?list=PLmXKhU9FNesSFvj6gASuWmQd23Ul5omtD Digital Electronics: https://www.youtube.com/playlist?list=PLmXKhU9FNesSfX1PVt4VGm-wbIKfemUWK Discrete Mathematics: Relations:https://www.youtube.com/playlist?list=PLmXKhU9FNesTpQNP_OpXN7WaPwGx7NWsq Graph Theory: https://www.youtube.com/playlist?list=PLmXKhU9FNesS7GpOddHDX3ZCl86_cwcIn Group Theory: https://www.youtube.com/playlist?list=PLmXKhU9FNesQrSgLxm6zx3XxH_M_8n3LA Proposition:https://www.youtube.com/playlist?list=PLmXKhU9FNesQxcibunbD82NTQMBKVUO1S Set Theory: https://www.youtube.com/playlist?list=PLmXKhU9FNesTSqP8hWDncxpCj8a4uzmu7 Data Structure: https://www.youtube.com/playlist?list=PLmXKhU9FNesRRy20Hjr2GuQ7Y6wevfsc5 Computer Networks: https://www.youtube.com/playlist?list=PLmXKhU9FNesSjFbXSZGF8JF_4LVwwofCd Algorithm: https://www.youtube.com/playlist?list=PLmXKhU9FNesQJ3rpOAFE6RTm-2u2diwKn • About this video: This video discusses the concept of Indexing in database in Hindi. Important topic of database Indexing like need of indexing in database management indexing, Why we do indexing in files in database, How we do indexing in dbms, Types of indexing, Methods of Indexing, Advantages of Indexing, How to access a file fast in database, Single level Indexing in database file, Multilevel indexing in database file structure in dbms, Dense indexing in database, Sparse Indexing in database, Index file in dbms, Advantages of using Index file in database are discussed. What is Indexing: Additional auxiliary access structure is called indexes, a data technique to efficiently retrieve records from the database files based on some attributes on which the indexing has been done. Dense Index: 1)In dense index, there is an entry in the index file for every search key value in the main file. This makes searching faster but requires more space to store index records itself. 2)Note that it is not for every record, it is for every search key value. Sometime number of records in the main file is greater than = number of search keys in the main file, for example if search key is repeated. Sparse Index: 1)If an index entry is created only for some records of the main file, then it is called sparse index. 2)No. of index entries in the index file is less than No. of records in the main file. Indexing in dbms, Indexing in dbms tutorial in hindi,about indexing in dbms,indexing and hashing in dbms, terminologies in indexing in database,indexing in dbms example,indexing in dbms tutorial,disadvantages of indexing in dbms,indexing in dbms for gate, sparse indexing example, dense indexing in dbms example, DBMS blueprint, DataBase Management system,database,DBMS, RDBMS, Relations, Table, Query, Normalization, Normal forms,Database design,Relational Model,Instance,Schema,Data Definition Language, SQL queries, ER Diagrams, Entity Relationship Model,Constraints,Entity,Attributes,Weak entity, Types of entity,DataBase design, database architecture, Degree of relation,Cardinality ratio,One to many relationship,
Views: 191664 KNOWLEDGE GATE
Oracle Database Indexes: Myths, Tips and Tricks
 
09:04
In this tutorial, OCM John Watson will - via demonstrations - debunk these myths: Myth #1: Oracle Database does not index NULL Myth #2: A search that includes wildcards can't use an index if the wildcard precedes the string. Myth #3: Oracle will not use a function-based index unless the FBI is coded in the predicate. Myth #4: Indexes always help. The more indexes the better. See http://skillbuilders.com/free-oracle-tutorials for gigabytes of free Oracle video tutorials.
Views: 16460 SkillBuilders
Understanding the use of GROUP BY clause in SQL
 
04:39
Join discussion: http://www.techtud.com/video-lecture/understanding-group-clause-sql IMPORTANT LINKS: 1) Official Website: http://www.techtud.com/ 2) Virtual GATE: http://virtualgate.in/login/index.php Both of the above mentioned platforms are COMPLETELY FREE, so feel free to Explore, Learn, Practice & Share! Our Social Media Links: Facebook Page: https://www.facebook.com/techtuduniversity Facebook Group: https://www.facebook.com/groups/virtualgate Google+ Page: https://plus.google.com/+techtud/posts Last but not the least, SUBSCRIBE our YouTube channel to stay updated about the regularly uploaded new videos.
Views: 81342 Techtud
14.416 Sort-Merge Join, Co-Grouping
 
18:31
My book "Patterns in Data Management" is now available both as an ebook or a print book (with color graphics!). See: http://amzn.to/1Ts3rwx This book is not a standard textbook on database techniques. This book was written extending and complementing preexisting educational videos (including this one). Video for my inverted classroom "Database Systems". The complete list of videos, slides, and additional material is (will be) available at http://datenbankenlernen.de Computer Science, Saarland University: Bachelor (in German): http://www.cs.uni-saarland.de/index.p... Master (in English): http://www.cs.uni-saarland.de/index.p... Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/
Oracle SQL Tuning, Join Order, The Closest Thing to a Silver Bullet
 
01:58
SQL Tuning, in Oracle Database or any other, is not always easy. We've found that after the most basic problems (e.g. index not available) the Join Order is often the cause of a problem and - because it can offer such great improvement - the closest thing to a Silver Bullet for Oracle SQL Tuning. Lessons 2 and 3 are also free, at https://www.skillbuilders.com/free-oracle-database-tutorials/tuning-oracle-sql-get-best-join-order/.
Views: 1876 SkillBuilders
47. Order By Clause in Oracle
 
03:20
In this video you will learn about Order By Clause in Oracle. ORDER BY clause is used to sort the records in the result set for a SELECT statement. Watch the video to learn more. For Support =========== Email: [email protected] Contact Form: http://www.learninhindi.com/home/contact Our Social Media ================ Facebook: https://www.facebook.com/LearnInHindi Twitter: https://twitter.com/LearnInHindi For Training & Videos ===================== For more videos and articles visit: http://www.learninhindi.com Free Java Programming In Hindi Course ===================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAwwhMyoLISrxkXTADGp7PH Free Oracle PL/SQL Programming In Hindi Course ============================================== https://www.youtube.com/playlist?list=PLB5DA82419C2D99B6 Free C Programming In Hindi Course ================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAxKpBLMWogxSdy6BZcsAJq Trips & Tricks Channel ====================== https://www.youtube.com/channel/UCGmLfkuCo-3lHHJXRJ9HUMw Programming in Hindi Channel ============================ https://www.youtube.com/channel/UCudElIDgwNrybeAvXIy1HZQ
Views: 14328 ITORIAN
Oracle PL SQL interview question NULL and Order by Clause
 
05:34
Oracle PL SQL interview question NULL and Order by Clause Click here to subscribe to my youtube channel http://www.youtube.com/channel/UCBt6VrxAIb5jLh9HLDcdwtQ?sub_confirmation=1 Oracle Interview questions and Answers at https://www.youtube.com/playlist?list=PLb1qVSx1k1Vr0v4wVyvT3GEuA0J0M4xBm Oracle 18C New features at https://www.youtube.com/playlist?list=PLb1qVSx1k1Vqe06V1tIBcvnslMPWX69bW Oracle 12C New features at https://www.youtube.com/playlist?list=PLb1qVSx1k1VqM1u2IHWzZIgziqejl6wx- Oracle PLSQL records and collections at https://www.youtube.com/playlist?list=PLb1qVSx1k1VpAFTXopXvAh_D3PLcTntdm
Views: 670 Siva Academy
Part 1   How to find nth highest salary in sql
 
11:45
Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/05/part-1-how-to-find-nth-highest-salary_17.html This is a very common SQL Server Interview Question. There are several ways of finding the nth highest salary. By the end of this video, we will be able to answer all the following questions as well. How to find nth highest salary in SQL Server using a Sub-Query How to find nth highest salary in SQL Server using a CTE How to find the 2nd, 3rd or 15th highest salary Let's use the following Employees table for this demo Use the following script to create Employees table Create table Employees ( ID int primary key identity, FirstName nvarchar(50), LastName nvarchar(50), Gender nvarchar(50), Salary int ) GO Insert into Employees values ('Ben', 'Hoskins', 'Male', 70000) Insert into Employees values ('Mark', 'Hastings', 'Male', 60000) Insert into Employees values ('Steve', 'Pound', 'Male', 45000) Insert into Employees values ('Ben', 'Hoskins', 'Male', 70000) Insert into Employees values ('Philip', 'Hastings', 'Male', 45000) Insert into Employees values ('Mary', 'Lambeth', 'Female', 30000) Insert into Employees values ('Valarie', 'Vikings', 'Female', 35000) Insert into Employees values ('John', 'Stanmore', 'Male', 80000) GO To find the highest salary it is straight forward. We can simply use the Max() function as shown below. Select Max(Salary) from Employees To get the second highest salary use a sub query along with Max() function as shown below. Select Max(Salary) from Employees where Salary [ (Select Max(Salary) from Employees) To find nth highest salary using Sub-Query SELECT TOP 1 SALARY FROM ( SELECT DISTINCT TOP N SALARY FROM EMPLOYEES ORDER BY SALARY DESC ) RESULT ORDER BY SALARY To find nth highest salary using CTE WITH RESULT AS ( SELECT SALARY, DENSE_RANK() OVER (ORDER BY SALARY DESC) AS DENSERANK FROM EMPLOYEES ) SELECT TOP 1 SALARY FROM RESULT WHERE DENSERANK = N To find 2nd highest salary we can use any of the above queries. Simple replace N with 2. Similarly, to find 3rd highest salary, simple replace N with 3. Please Note: On many of the websites, you may have seen that, the following query can be used to get the nth highest salary. The below query will only work if there are no duplicates. WITH RESULT AS ( SELECT SALARY, ROW_NUMBER() OVER (ORDER BY SALARY DESC) AS ROWNUMBER FROM EMPLOYEES ) SELECT SALARY FROM RESULT WHERE ROWNUMBER = 3
Views: 1002506 kudvenkat
Database - Indexes And Optimization
 
10:04
Covers the basic concepts of database indexes and using them to optimize a database
Tune Your Oracle SQL Without Hints or Indexes! - Preview Introduction
 
00:58
“But I can’t change the queries that run in my database,” you say. Not a problem! This webinar we explore the underutilized art of rewriting a SQL query in order to make it run faster. I'll show you how to make your SQL query performance skyrocket simply by changing the SQL text. But even if you truly can't change the SQL, I'll also demonstrate how you can hurdle this issue too. This webinar will be presented by our most active OraPub SLACK member, Kaley Crum! Go Kaley!! This webinar will be on Wed Sept 12th 2018 at 7am PT. For details on how you can see the full webinar or webinar recording post date, go to www.orapub.com
Views: 32 OraPub, Inc.
How Many Indexes Are Too Many?: Finding All The Red Sweets Part 5
 
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Every index you add to a table increases its storage requirements and DML overheads. So it's a good idea to create as few as possible. When you have two or more indexes using the same columns, you may be able to get away with just one. But how do you decide which to keep? This video discusses how to analyze your queries so you can cut the number of indexes you create. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 2473 The Magic of SQL
Things every developer absolutely, positively needs to know about database indexing - Kai Sassnowski
 
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Join Europe's leading Laravel conference in 2019. 23th May in Madrid & 28th–30th Aug in Amsterdam. Get Tickets http://laracon.eu/2019
Views: 3916 Laracon EU
Differences between Clustered vs Nonclustered Indexes in SQL Server
 
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Should you use a clustered or a nonclustered index? When starting out with SQL, you might intuitively know that you should add an index to a table, but you might not be sure what kind of index to add. In this video we go over the basics of clustered and nonclustered indexes to help you get through index choice paralysis. Blog post with example queries: https://bertwagner.com/2017/09/26/clustered-vs-nonclustered-index-fundamentals-you-need-to-know/ Follow me on Twitter: https://twitter.com/bertwagner Want to receive my latest weekly blog posts and videos in your inbox? Sign up for the newsletter here: https://upscri.be/c77fc8/
Views: 7646 Bert Wagner
SQL SERVER – Index Usage (Improve Performance)
 
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**** SysInfoTools DATABASE RECOVERY (REPAIR CORRUPTION) **** 👉https://order.shareit.com/product?vendorid=200149662&productid=300612508&languageid=1&affiliateid=200282640 **** SysInfoTools DATABASE RECOVERY TOOLKIT (REPAIR CORRUPTION + PASSWORD RECOVERY) **** 👉https://order.shareit.com/product?vendorid=200149662&productid=300725598&languageid=1&affiliateid=200282640 **** SysInfoTools SQL SERVER PASSWORD RECOVERY **** 👉https://order.shareit.com/product?vendorid=200149662&productid=300606987&languageid=1&affiliateid=200282640 Are you unsure if your SQL Server Indexes are being used effectively by SQL Queries? What if your Unused SQL Server Indexes are causing a lot of Overhead on Inserts, Updates, and Deletes? In my career, I’ve experimented with numerous SQL scripts for Index Usage. This YouTube video explains the Index Usage Script in Depth, which has been the most effective script that I’ve worked with in Large Scale environments to find SQL Server unused indexes. **** Blog Post Link with Step-By-Step Instructions Below **** ========================================== https://joshburnstech.com/2019/01/sql-server-index-usage-query-script/ ========================================== **** Important Link to Click! **** https://www.youtube.com/channel/UCQZ9jWTa3xpyUAPgNnAHRpw/example?sub_confirmation=1 **** What I'm Reading **** =================================================================== Automate the Boring Stuff with Python: Practical Programming for Total Beginners https://amzn.to/2HG6EJZ =================================================================== **** Section Times in Video **** ========================================= #1: Open the Index Usage Blog Post 0:32 #2: Copy the Index Usage SQL Script 1:39 #3: Paste the SQL Script in SSMS 3:06 #4: Execute the SQL Script 3:21 #5: Modify the WHERE Clause 4:25 #6: Post any Questions! (I will reply) 7:43 ========================================= My 4K YouTube Setup Gear (How the video was recorded): ========================================== https://kit.com/JoshBurnsTech/youtube-setup-gear ========================================== Edited by: Alex Zingaro ======================== http://www.alexzingaro.com/ ======================== LET'S CONNECT! 📷 Instagram ➔ https://www.instagram.com/joshburnstech/ 📱 Facebook ➔ https://www.facebook.com/JoshBurnsTech/ 🐦 Twitter ➔ https://twitter.com/JoshBurnsTech 🙋🏼‍♂️ Website ➔ https://JoshBurnsTech.com DISCLAIMER: This video and description contains affiliate links, which means that if you click on one of the product links, I’ll receive a small commission.
Views: 614 Josh Burns Tech
SQL index
 
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. Index 1) Why indexes? Indexes are used by queries to find data from tables quickly. Indexes are created on tables and views. Index on a table or a view, is very similar to an index that we find in a book. Clustered and Non-Clustered indexes Note that Id column is marked as primary key. Primary key, constraint create clustered indexes automatically if no clustered index already exists on the table and a nonclustered index is not specified when you create the PRIMARY KEY constraint. a clustered index dictates the physical storage order of the data in a table, a table can contain only one clustered index. A clustered index is analogous to a telephone directory Non Clustered Index: A nonclustered index is analogous to an index in a textbook. The data is stored in one place, the index in another place. Difference between Clustered and NonClustered Index: 1. Only one clustered index per table, where as you can have more than one non clustered index 2. Clustered index is faster than a non clustered index, because, the non-clustered index has to refer back to the table, if the selected column is not present in the index. 3. Clustered index determines the storage order of rows in the table, and hence doesn't require additional disk space, but where as a Non Clustered index is stored seperately from the table, additional storage space is required. Unique index is used to enforce uniqueness of key values in the index. Let's understand this with an example. Note: 1. By default, a PRIMARY KEY constraint, creates a unique clustered index, where as a UNIQUE constraint creates a unique nonclustered index. These defaults can be changed if you wish to. 2. A UNIQUE constraint or a UNIQUE index cannot be created on an existing table, if the table contains duplicate values in the key columns. Obviously, to solve this,remove the key columns from the index definition or delete or update the duplicate values. 3. By default, duplicate values are not allowed on key columns, when you have a unique index or constraint. For, example, if I try to insert 10 rows, out of which 5 rows contain duplicates, then all the 10 rows are rejected. However, if I want only the 5 duplicate rows to be rejected and accept the non-duplicate 5 rows, then I can use IGNORE_DUP_KEY option. An example of using IGNORE_DUP_KEY option is shown below.
Views: 19 R K
Oracle SQL Tutorial 4 - Beginner Terms - Database Design Primer 1
 
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The terms covered in this video are: SQL RDBMS Relations NULL Database design Relationships Primary key Foreign key Constraint Indexes Data type HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 71083 Caleb Curry
Row Number function in SQL Server
 
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sql server row_number example sql server row number by partition sql server row_number over partition by order by In this video we will discuss Row_Number function in SQL Server. This is continuation to Part 108. Please watch Part 108 from SQL Server tutorial before proceeding. Row_Number function Introduced in SQL Server 2005 Returns the sequential number of a row starting at 1 ORDER BY clause is required PARTITION BY clause is optional When the data is partitioned, row number is reset to 1 when the partition changes Syntax : ROW_NUMBER() OVER (ORDER BY Col1, Col2) Row_Number function without PARTITION BY : In this example, data is not partitioned, so ROW_NUMBER will provide a consecutive numbering for all the rows in the table based on the order of rows imposed by the ORDER BY clause. SELECT Name, Gender, Salary, ROW_NUMBER() OVER (ORDER BY Gender) AS RowNumber FROM Employees Please note : If ORDER BY clause is not specified you will get the following error The function 'ROW_NUMBER' must have an OVER clause with ORDER BY Row_Number function with PARTITION BY : In this example, data is partitioned by Gender, so ROW_NUMBER will provide a consecutive numbering only for the rows with in a parttion. When the partition changes the row number is reset to 1. SELECT Name, Gender, Salary, ROW_NUMBER() OVER (PARTITION BY Gender ORDER BY Gender) AS RowNumber FROM Employees Use case for Row_Number function : Deleting all duplicate rows except one from a sql server table. Discussed in detail in Part 4 of SQL Server Interview Questions and Answers video series. Text version of the video http://csharp-video-tutorials.blogspot.com/2015/09/rownumber-function-in-sql-server.html Slides http://csharp-video-tutorials.blogspot.com/2015/09/rownumber-function-in-sql-server_30.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 90351 kudvenkat
Oracle Partition By clause, Oracle Analytic Functions tutorial
 
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More about analytic functions, visit https://www.youtube.com/watch?v=Ukekis8C-SI&list=PL99-DcFspRUoscBHdh39T8EHENfm2VcQ3&index=2 Oracle Analytic Functions and Over By Partition clause enable calculating cumulative and moving aggregates returning multiple rows for each group.
SQL Server - SQL Server Group By Index
 
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Curso Oracle PL/SQL Essentials http://bit.ly/1N3upVn Curso Oracle SQL Expert - Certificação 1Z0-047 http://bit.ly/1G4rKWG Curso Oracle Aprendendo SQL - Preparatório exames 1Z0-051/1Z0-061 http://bit.ly/1eqDlsr Curso de Administração de Redes de Computadores http://goo.gl/nXjaXS Que tal Aprender PHP Orientado a Objetos do Jeito Certo? Aprender a Criar um Framework PHP, Seu Próprio Painel de Controle e um Guia Comercial! http://goo.gl/Yy3QvB Curso de SQL Server - Aprenda neste ótimo curso de SQL Server conceitos desde a introdução, passando pela instalação, conceitos de bancos de dados, modelagem e programação SQL. Ao fazer o Curso de SQL Server você estará apto a desempenhar funções como administrador de bancos de dados SQL Server. Este Curso de SQL Server foi desenvolvido com uma didática simples e de facil entendimento. O Curso é oferecido gratuitamente aqui porém caso tenha interesse em se aprofundar e aprender outros sistemas de bancos de dados a fundo acesse os links acima. Também acesse o link de administração de redes de computadores para mais conhecimento nesta área tornando-se um profissional completo. Tags: SQL Server SQL Server 2008 SQL Server 2012 cursos gratuitos banco de dados sgbd
Views: 1903 Cursos Interativos
Oracle: Tune Your SQL Without Hints or Indexes! - Long Introduction
 
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"But I can’t change the queries that run in my database,” you say. Not a problem! This webinar we explore the underutilized art of rewriting a SQL query in order to make it run faster. I'll show you how to make your SQL query performance skyrocket simply by changing the SQL text. But even if you truly can't change the SQL, I'll also demonstrate how you can hurdle this issue too. This webinar will be presented by our most active OraPub SLACK member, Kaley Crum! To watch the full webinar go to www.oraoub.com/webinars
Views: 59 OraPub, Inc.
Locking in Oracle | Oracle SQL Tutorial Videos | Mr.Vijay Kumar
 
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Locking in Oracle | Oracle SQL Tutorial Videos | Mr.Vijay Kumar ** For Online Training Registration: https://goo.gl/r6kJbB ► Call: +91-8179191999 💡 Visit Our Website for Classroom Training: https://nareshit.in/oracle-training/ 💡 For Online Training: https://nareshit.com/oracle-online-training/ #Oracle #Training #CourseVideos -------------------------- 💡 About NareshIT: "Naresh IT is having 14+ years of experience in software training industry and the best Software Training Institute for online training, classroom training, weekend training, corporate training of Hadoop, Salesforce, AWS, DevOps, Spark, Data Science, Python, Tableau, RPA , Java, C#.NET, ASP.NET, Oracle, Testing Tools, Silver light, Linq, SQL Server, Selenium, Android, iPhone, C Language, C++, PHP and Digital Marketing in USA, Hyderabad, Chennai and Vijayawada, Bangalore India which provides online training across all the locations -------------------------- 💡 Our Online Training Features: 🎈 Training with Real-Time Experts 🎈 Industry Specific Scenario’s 🎈 Flexible Timings 🎈 Soft Copy of Material 🎈 Share Videos of each and every session. -------------------------- 💡 Please write back to us at 📧 [email protected]/ 📧 [email protected] or Call us at the USA: ☎+1404-232-9879 or India: ☎ +918179191999 -------------------------- 💡 Check The Below Links ► For Course Reg: https://goo.gl/r6kJbB ► Subscribe to Our Channel: https://goo.gl/q9ozyG ► Circle us on G+: https://plus.google.com/+NareshIT ► Like us on Facebook: https://www.facebook.com/NareshIT ► Follow us on Twitter: https://twitter.com/nareshitek ► Follow us on Linkedin: https://goo.gl/CRBZ5F ► Follow us on Instagram: https://goo.gl/3UXYK3
Views: 24751 Naresh i Technologies
Making Smart Scan for Exadata Work (Demonstration)
 
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Making Smart Scan Work - Demo I'll go through a simple example of the kind of thing we need to think about when trying to achieve Smart Scan. Let me just enable tracing, run a simple query, select and * from *. Now, there's my query. The result set comes back, and how is it executed? An index full scan with the PK* index. The optimizer is intelligent enough to know that my query can be satisfied purely by reading the index and therefore it didn't have to go to the table at all. It looks very good. Well, it wasn't. Index full scans are an operation that cannot be offloaded. So, to execute that statement, every block of that index was delivered into the buffer cache of my own database instance, and the compute node then has to do the work of extracting those values. What can we do about it? One solution would be to hint the code. I select and demand an index fast full scan, and now we see the magic word "storage." An index fast full scan is offloadable, because an index fast full scan can do direct reads. An alternative approach? Well, you might not want to hint many, many thousands of lines of code. An alternative approach would be to do it through DDL. For example, take that index, make it invisible. Now run my statements without any hint at all, table access storage full, and that was offloaded. Having made the index invisible, Oracle has no option but a full-table scan, and a full-table scan is offloadable. Now, this means I have three options of this very simple example. I can let the optimizer get on with what it wants to do, and then I use an index that I'm doing block serving into the buffer cache. I can hint the code, index fast full scan. That's probably the best option for performance, but it's also the most work. In this intervening case, I make the index invisible so that it will still be used of course for enforcing the primary key constraints, but it will not be visible to the optimizer and therefore influence the optimizer towards using plans that can be offloaded the Smart Scan. Making the choice between this and influencing the optimizer in the correct direction is an extremely difficult job, and it is not always easy to determine what is going to be the best solution.
Views: 3704 SkillBuilders
SQL Joins, nested loops and all that in less than 6 minutes
 
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CAPTIONS AVAILABLE - Full transcript (with some screenshots) available for a small fee at http://stores.lulu.com/konagora/. A very brief description of how a database performs a join, based on material from a 2-day seminar.
Views: 77961 roughsealtd
ROWID VS ROWNUM IN ORACLE
 
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This Video explains the difference between ROWID and ROWNUM using real project examples. ROWID provides the unique physical address where the row is being stored. ROWNUM indicates the order in which the data was returned from the select query.
Views: 4223 Tech Coach
SQL Tutorial - 03 - Create - Database, Table, Index
 
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This SQL tutorial lives at: http://www.pvtuts.com/sql/sql-create The video describes how to create databases, tables, and indexes.
Views: 87934 ProgrammingVideos
Chapter 15 to Chapter 18 : Index, Synonym & Data Dictionary
 
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Indexes Indexes are the database objects that are used to tune the performance of the SELECT query.There are different types of indexes including those used to enforce primary key constraints,unique indexes,non-unique indexes,and concatenated indexes,among others.Without indexes,queries would require Oracle to scan all rows in a table in order to return the required rows for the result table.An index is created on table columns,which then stores all the values of the column under index segment.Unlike sequence,indexes are table specific.They are automatically dropped once the table has been dropped. Synonyms A synonym is an alias,that is,a form of shorthand used to simplify the task of referencing a database object.The concept is analogous to the use of nicknames for friends and acquaintances.Referencing an object owned by another user requires the schema name to be prefixed with it. With the help of a synonym, you reduce the effort of referencing the object along with the schema name.In this way, synonym provides location transparency because the synonym name hides the actual object name and its owner.
14.410 Applications of Join Algorithms, Nested-Loop Join, Index Nested-Loop Join
 
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My book "Patterns in Data Management" is now available both as an ebook or a print book (with color graphics!). See: http://amzn.to/1Ts3rwx This book is not a standard textbook on database techniques. This book was written extending and complementing preexisting educational videos (including this one). Video for my inverted classroom "Database Systems". The complete list of videos, slides, and additional material is (will be) available at http://datenbankenlernen.de Computer Science, Saarland University: Bachelor (in German): http://www.cs.uni-saarland.de/index.p... Master (in English): http://www.cs.uni-saarland.de/index.p... Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/
Oracle Part 6 Primary Key
 
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Primary key, varchar, length, trim, order by clause
Views: 1130 Free OpenMentor