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 !!?
Answer Posted / 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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hi,i plan to put experience on PLSQL ,can anyone suggest me for any institutes in bangalore or how to prepare for interviews
Which is faster count (*) or count 1?
First round ------------------- - Procedure - Packages - Views - Virtual tables - Can we use dcl with in function? - Joins and few scenarios - Triggers and its type - Pragma, type and its functionality - How to create db link in oracle - Materialized view - How to find duplicate values from table? - Cursor and its functionality - Write a script to display friday and its date from a entire year. - Exception Handling Second round ------------------------ Gave a scenario like. Need to write a function to perform. When user try to change a password. It must not be last five password and a given password can be combination of characters, symbols, upper and lower case.
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