SQL filtering by multiple columns

Question

I have a MySql table, which I want to query for rows in which pairs of columns are in a specific set. For example, say my table looks like this:

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Answer 1

A rough but practical way is to use string concatenation:

SELECT *
FROM MyTable
WHERE CONCAT(f1, '_', f2) IN ('a_30', 'b_20')

Answer 2

SELECT * FROM my_table WHERE (f1= 'a' AND f2=30) OR (f1='b' AND f2=20);

Answer 3

That is valid syntax.

If you don't like it some other alternatives are:

SELECT * FROM my_table
WHERE (f1, f2) = ('a', 30)
OR    (f1, f2) = ('b', 20)

Or using a join:

SELECT *
FROM my_table T1
(
    SELECT 'a' AS f1, 30 AS f2
    UNION ALL
    SELECT 'b', 20
) T2
ON T1.f1 = T2.f1 AND T1.f2 = T2.f2