Performance tuning Steps

Steps to Tune the Query :
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1.Make sure the proper joins for whatever tables in from clause.
2.Make the joins with "ID's" instead of Database columns.
3.Avoid Multitable views, Use Org Specific views whereever possible.
4.If the custom table is having large amount of create indexes.
5.Avoid Type casting and Aggregate functions,Negation operators
   on Indexed columns.
6.Instead of using the whole query in a single cursor or group ,
   split into multiple   Groups and link them.
7. use union all instead of Union
8. Use Exists inplace of in
9. Avoid usage of Negation operators like NOT, !=.
10.Use Union instead of OR Clause.
11.Avoid Usage of outer joins , use Equi joins whereever possible
12.Use Where Clause instead of Having Clause.