Comments on: SQL SERVER – Correlated and Noncorrelated – SubQuery Introduction, Explanation and Example http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/ Notes of a SQL Server MVP and Database Administrator Wed, 17 Mar 2010 18:05:10 +0000 http://wordpress.com/ hourly 1 By: Marko Parkkola http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61920 Marko Parkkola Sun, 28 Feb 2010 10:56:31 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61920 I've understood that you make the most limiting joins first. Then proceed with all the others. But simply test it! Write your query in different ways and measure how long they take. Check also the Execution Plan in order to find out if you need to add indexes. But I must confess that I don't always practice what I preach. I'm currently dealing with queries where I have to make many OUTER and INNER JOINs, many subqueries, groupings and calculations. I just write good enough query and if it's too slow it is caught in the tests and it's sent back to me, and then I try to optimize it. I'm getting lazy :( I’ve understood that you make the most limiting joins first. Then proceed with all the others.

But simply test it! Write your query in different ways and measure how long they take. Check also the Execution Plan in order to find out if you need to add indexes.

But I must confess that I don’t always practice what I preach. I’m currently dealing with queries where I have to make many OUTER and INNER JOINs, many subqueries, groupings and calculations. I just write good enough query and if it’s too slow it is caught in the tests and it’s sent back to me, and then I try to optimize it.

I’m getting lazy :(

]]> By: Praveen http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61906 Praveen Sun, 28 Feb 2010 00:51:22 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61906 Actually if you can post something on order of joins to be followed when working with ..say 5 to 10 tables, it will be great. as the joins increase then how should be order of table to be appearing in join. Actually if you can post something on order of joins to be followed when working with ..say 5 to 10 tables, it will be great. as the joins increase then how should be order of table to be appearing in join.

]]> By: Praveen http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61905 Praveen Sun, 28 Feb 2010 00:48:50 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61905 Good one, you are making life simpler for lots of them out here. congrats. Good one, you are making life simpler for lots of them out here. congrats.

]]> By: Pinal Dave http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61412 Pinal Dave Thu, 18 Feb 2010 11:16:09 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61412 Hello Pawan, The values of two columns can be swapped using simple update statement like: UPDATE tblTable SET col1 = col2, col2 = col1 Regards, Pinal Dave Hello Pawan,

The values of two columns can be swapped using simple update statement like:

UPDATE tblTable
SET col1 = col2,
col2 = col1

Regards,
Pinal Dave

]]> By: pawan http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61373 pawan Wed, 17 Feb 2010 16:24:46 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-61373 hello pinal, Wish you all happiness. I too read your articles, It is very good. pinal please give me the solution of this question. suppose we have a table and two columns ........ Now the question is we have to interchange the values of this columns using single query. please suggest the solution , thanks and regards pawan hello pinal,
Wish you all happiness. I too read your articles, It is very good.

pinal please give me the solution of this question.

suppose we have a table and two columns ……..
Now the question is we have to interchange the values of
this columns using single query.

please suggest the solution ,

thanks and regards
pawan

]]> By: Chintan http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-60637 Chintan Thu, 04 Feb 2010 05:20:29 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-60637 Good article...Dave keep posting Regards, Chintan, Bangalore Good article…Dave

keep posting

Regards,
Chintan, Bangalore

]]> By: riaz mohamed http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-57176 riaz mohamed Fri, 30 Oct 2009 12:01:19 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-57176 hi brother.... i am studying sql. Can i get solved subqueries tutorial. hi brother…. i am studying sql. Can i get solved subqueries tutorial.

]]> By: vidya http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-56743 vidya Fri, 16 Oct 2009 03:35:48 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-56743 i want some full material about SQLSERVER 2005 i want some full material about SQLSERVER 2005

]]> By: katheesh kumar http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-51920 katheesh kumar Fri, 15 May 2009 12:31:16 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-51920 anyone who sees this site should improve his knowledge on sql fine work and it should be praised! anyone who sees this site should improve his knowledge on sql fine work and it should be praised!

]]> By: SQL SERVER - 2008 - Interview Questions and Answers - Part 2 Journey to SQL Authority with Pinal Dave http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-42749 SQL SERVER - 2008 - Interview Questions and Answers - Part 2 Journey to SQL Authority with Pinal Dave Sat, 13 Sep 2008 01:31:48 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-42749 [...] A subquery is a SELECT statement that is nested within another T-SQL statement. A subquery SELECT statement if executed independently of the T-SQL statement, in which it is nested, will return a resultset. Meaning a subquery SELECT statement can standalone and is not depended on the statement in which it is nested. A subquery SELECT statement can return any number of values, and can be found in, the column list of a SELECT statement, a FROM, GROUP BY, HAVING, and/or ORDER BY clauses of a T-SQL statement. A Subquery can also be used as a parameter to a function call. Basically a subquery can be used anywhere an expression can be used. (Read More Here) [...] [...] A subquery is a SELECT statement that is nested within another T-SQL statement. A subquery SELECT statement if executed independently of the T-SQL statement, in which it is nested, will return a resultset. Meaning a subquery SELECT statement can standalone and is not depended on the statement in which it is nested. A subquery SELECT statement can return any number of values, and can be found in, the column list of a SELECT statement, a FROM, GROUP BY, HAVING, and/or ORDER BY clauses of a T-SQL statement. A Subquery can also be used as a parameter to a function call. Basically a subquery can be used anywhere an expression can be used. (Read More Here) [...]

]]> By: Swapnil Mohod http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-25580 Swapnil Mohod Wed, 12 Dec 2007 17:10:55 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-25580 As per books available in the market,it says DELETE table can be ROLLBACK while TRUNCATE table CANNOT be ROLLBACK, But it is paractically wrong,Both can be roll back... Then why this is so............... As per books available in the market,it says
DELETE table can be ROLLBACK while
TRUNCATE table CANNOT be ROLLBACK,
But it is paractically wrong,Both can be roll back…
Then why this is so……………

]]> By: Swapnil Mohod http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-22097 Swapnil Mohod Fri, 23 Nov 2007 12:08:59 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-22097 Good One.... Good One….

]]> By: chanti http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-14123 chanti Tue, 25 Sep 2007 20:53:16 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-14123 Hi Aavesh, rowlock is Record wise lock on data. NoLock is for Object which will not lock any records & whick is not applicable to DML commands like insert, update & Delete commands Thanks, Chanti Hi Aavesh,

rowlock is Record wise lock on data.
NoLock is for Object which will not lock any records & whick is not applicable to DML commands like insert, update & Delete commands

Thanks,
Chanti

]]> By: Aavesh Agarwal http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-13756 Aavesh Agarwal Sun, 23 Sep 2007 15:46:42 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-13756 Hello Dave, Your site is really nice.can u send me those queries which generally asked in Interviews.I really need it.and more question What is the difference between rowLock and NO Lock. Thanks and Regards Aavesh Agarwal Hello Dave,

Your site is really nice.can u send me those queries which generally asked in Interviews.I really need it.and more question What is the difference between rowLock and NO Lock.

Thanks and Regards
Aavesh Agarwal

]]> By: kaviarasu http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-13716 kaviarasu Sun, 23 Sep 2007 08:51:48 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-13716 I am kaviarasu.I am learning Oracle DBA and i am going to write the certification.Could you sed me the Oracle SQL questions to the above e-mail id. I am kaviarasu.I am learning Oracle DBA and i am going to write the certification.Could you sed me the Oracle SQL questions to the above e-mail id.

]]> By: T.Manikumar http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-11716 T.Manikumar Sat, 08 Sep 2007 07:45:34 +0000 http://blog.sqlauthority.com/2007/09/07/sql-server-correlated-and-noncorrelated-subquery-introduction-explanation-and-example/#comment-11716 Sir, I saw your website its really super it very help full to beginners and improve our knowledge this website because it can easily to understand them. I have lots of doutes in the sql server pls send to my mail -id daily some tips and tricks in sql server sir. Thanks, T.Manikumar Sir,
I saw your website its really super it very help full to beginners and improve our knowledge this website because it can easily to understand them.

I have lots of doutes in the sql server pls send to my mail -id daily some tips and tricks in sql server sir.

Thanks,
T.Manikumar

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