Can any one tell me how to increase the performance of a sql query ie what are

Can any one tell me how to increase the performance of a
sql query ie what are the performance tips in creating or
writing a sql query !!?

Question Posted / lalamaheshkumar

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Can any one tell me how to increase the performance of a sql query ie what are the performance tip..

Answer / manoj

1.
Use proper sequence of tables in from clause
i.e.
the table have more common column must in last
in form clause bcoz on firing of query engine link
last table in form clause
2.
Use "Exist" clause instead of "Not in"
Bcoz it return only true/false(boolean)

3.
Use "Hint" if Required

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Can any one tell me how to increase the performance of a sql query ie what are the performance tip..

Answer / sathishrpillai

Hii..
for optimization of sql query
1.don't use select * from,choose particular fields itself
2.don't use both OR ,AND in same query
3.Minimise the use of aggreagate functions such sum,count
4.don't link unneccessary tables

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Can any one tell me how to increase the performance of a sql query ie what are the performance tip..

Answer / hutashan

use Inline view to eleminate large number of rows
Avoid implicit datatype conversion
Avoid using function on an indexed column
Avoid comparing column value with NULL
Outer Join
Use OR carefully

Do not use outer join unless absolutely necessary. Degree
of optimizing outer join permutation is VERY LIMITED
Instead: Consider using default values in the base table to
avoid outer join
Do not outer join to a view. This typically results in a
non-mergable view execution plan
Always use NOT EXISTS instead of NOT IN

Remove DISTINCT keyword from SELECT if UNION is used

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