mysql中如何查询B表中有多少记录的某字段等于A表的字段

SELECT count(b.aid) FROM b as b LEFT JOIN a as a ON b.aid = b.id
mysql中如何查询B表中有多少记录的某字段等于A表的字段
SELECT count(b.aid) FROM b as b
LEFT JOIN a as a
ON b.aid = b.id2013-09-29
select count(*) from b,a where b.aid=b.id2013-09-29
mengvlog 阅读 49 次 更新于 2025-10-30 21:34:49 我来答关注问题0
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