SQL:全部分组

Question

我想做以下伪SQL:

SUM( SELECT a FROM tab WHERE b > 0);

这种语法不起作用(至少在sqlite中不起作用),所以我试图弄清楚正确的措辞.

SELECT SUM(a) FROM tab WHERE b > 0 GROUP BY (*); % nope
SELECT SUM(a) FROM tab WHERE b > 0 GROUP BY (1); % nope

建议？

Answer 1

怎么了SELECT SUM(a) FROM tab WHERE b > 0？