On which columns you should create Indexes?

On which columns you should create Indexes?
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1 Answer

Answer :

In general, you should create an index on a column in any of the following situations:
▪ The column is queried frequently
▪ A referential integrity constraint exists on the column
▪ A UNIQUE key integrity constraint exists on the column
The following list gives guidelines in choosing columns to index:
▪ You should create indexes on columns that are used frequently in WHERE clauses
▪ Are used frequently to join tables
▪ Are used frequently in ORDER BY clauses
▪ On columns that have few of the same values or unique values in the table
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