Hi,

Here is the answer,

Sql Statements are used to retrieve data from the database. We can get same results by writing different sql queries. But use of the best query is important when performance is considered. So you need to sql query tuning based on the requirement. The query optimizer is the component of a database management system that attempts to determine the most efficient way to execute a query. The optimizer considers the possible query plans for a given input query, and attempts to determine which of those plans will be the most efficient.There are so many optimization techniques following steps are used to select best plans-

-Consider each possible plan in turn.

-Run it & measure performance.

-The one that was fastest is the keeper.