我试图计算 t2 的子集中有多少新元组与 t1 相比
SELECT
COUNT(t2.id)
FROM (
(SELECT id, col1 FROM t2 WHERE col2=0 AND col3=0) AS t
LEFT OUTER JOIN
t1
ON
t.id=t1.id
)
WHERE
t1.id IS NULL;
子集定义为
(SELECT id, col1 FROM t2 WHERE col2=0 AND col3=0) AS t
但是上面的程序似乎不起作用,发出错误。