云海网博客杂谈

mysql 查询多条a表信息，date字段等于2025，并且a表s字段在a表有多少条信息

SELECT distinct y1.`s`,(SELECT COUNT(*) FROM a y2 WHERE y2.b = y1.b and date="2025-07-17" and y2.s = y1.s) AS s_count FROM a y1 where date = "2025-07-17" and s="内容";

distinct y1.`s`去重表1s字段

COUNT(*)查询条数

a y2定义a表为y2量

WHERE y2.b = y1.b表条件

AS s_count定义新字段为s_count

mysql优化后

SELECT y1.`s`,COUNT(*) AS s_count FROM a表 y1 WHERE y1.date = "2025-07-17" AND y1.b字段 = "名" GROUP BY y1.s;