How improve performances of an SQL query ?

Question

when tables in databases contains a millions of rows , we can get a performance issues mainly in response time.

Answer 1

thank u for reply , using index can just reduce response time but it's still take many seconds.

Answer 2

Try an Index in your table.
Don't use select * querys.

Answer 3

There are several answers to this question including: only use the fields that you truly need from the tables in your query, and use indexed fields in the WHERE clause of the SQL statement. Many interfaces that allow you to build SQL queries (MySQL Workbench, IB Expert, etc) typically have built-in performance tools that help you with optimizing your query.