How to use one or more OR and AND in mysql query [duplicate]

Answer 1

Please read below.

Is there a difference between these two queries?

You will get idea what is importance of parenthesis in OR and AND.

Answer 2

Use parentheses to set the priority of the logic expressions:

SELECT * FROM database_table WHERE (name = var1 OR name = var2 OR name = var3) AND id < 200

Answer 3

There is precedence with logical operators. When in doubt, use parenthesis.

In your case:

SELECT * FROM database WHERE (name = var1 OR name = var2 OR name = var3) AND id < 200

Your original query was interpreted as follows because the AND has higher precedence.

SELECT * FROM database WHERE name = var1 OR name = var2 OR (name = var3 AND id < 200)

Update

As commented by Rocket, you could condense your OR statements to IN since they operate on the same field. Doing so would remove the need for parentheses.

SELECT * FROM database WHERE name IN (var1,var2,var3) AND id < 200

Nonetheless, understanding the difference between the two original queries is important as you inevitably will write queries with multiple conditions.