Question

I wanted to get some clarification, if using OR in a sql statement on indexes does it use the index or no?

For example if I have this query:

SELECT * FROM account_orders WHERE accountid = 1 OR accountid = 0

I have an index on the accountid field

Will mysql use the index? Or would it be better to use a union? I keep reading that mysql doesnt use an index with an or statement, or perhaps Im reading that incorrectly. Any help/explanation would be helpful. Using mysql 5.x

Answer 1

Database won’t use an index if you use OR like you have.

The work around is to rephrase it using IN. as follows:

SELECT * FROM account_orders WHERE accountid IN (1, 0)

Databases will use an index (if available) with this syntax