如何优化来自同一表的多个SELECT的SQL查询？

Question

How can I optimizate this SQL Query?

(SELECT SUM (same_field) FROM same_table WHERE other_same_field = '0') AS a,
(SELECT SUM (same_field) FROM same_table WHERE other_same_field = '1') AS b,
(SELECT SUM (same_field) FROM same_table WHERE other_same_field = '2') AS c

Answer 1

When you want to do a pivot in MySQL you can do Aggregate on a Case statement

SELECT 
    SUM ( CASE WHEN other_same_field  = 0 THEN same_field ELSE 0 END) as A,
    SUM ( CASE WHEN other_same_field  = 1 THEN same_field ELSE 0 END) as B,
    SUM ( CASE WHEN other_same_field  = 2 THEN same_field ELSE 0 END) as C
FROM same_table
WHERE other_same_field IN (0, 1, 2)

Answer 2

This will give you a vertical result.

SELECT other_same_field, SUM(same_field)
FROM same_table
WHERE other_same_field IN (0, 1, 2)
GROUP BY other_same_field