Question

QUERY

SELECT *
FROM `products`
WHERE (
`category` = 'a'
AND `category` = 'b'
)

MySQL

products
---
id      sku     category
-------------------------
1       34343   a
2       32523   d
3       23234   b
4       23433   b
5       23442   c

I want to return A and B

Answer 1

SELECT *
FROM `products`
WHERE (
`category` = 'a'
OR `category` = 'b'
)

OR

SELECT *
FROM `products`
WHERE
`category` IN ('a', 'b')

You can use IN clause to replace many OR conditions. IN simply checks whether a value is within a set of values.