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sqllearner
Aged Yak Warrior
639 Posts |
 Posted - 2006-03-02 : 16:24:17
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| Iam using a stored procedure where the @emp_number is the input parameter and I want to know how internally this both queries work and which gives more performance....SELECT emp_name,emp_number,emp_state,emp_address,emp_statusFROM tbl_emp_infoWHERE emp_id = ( select max(emp_id) from tbl_emp_info WHERE emp_number = @emp_number and emp_status in ('Active') ) Here I declare a variable and get the max emp_id first and then pass it to the main query..Which one gives better performance and how does that internally fire in SQL server Delcare @max_emp_id INT SET @max_emp_id = select max(emp_id) from tbl_emp_info WHERE emp_number = @emp_number and emp_status in ('Active') SELECT emp_name,emp_number,emp_state,emp_address,emp_status FROM tbl_emp_info WHERE emp_id=@max_emp_id |
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sqllearner
Aged Yak Warrior
639 Posts |
Posted - 2006-03-02 : 16:54:07
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| Please let me know if somebody knows how internally this query gets executed |
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TG
Master Smack Fu Yak Hacker
6065 Posts |
Posted - 2006-03-02 : 16:57:57
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| You may be able to see for yourself. Have you compared the execution plans?(tools | options | connection properties tab | set showplan_text)run both queries. Sql server will output the execution plans for both.Be One with the OptimizerTG |
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Internal Working Mechanism in SQL Server