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  • 子查询

    不建议使用子查询,能用链接的用链接,子查询影响服务器性能。

    SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2);
    DELETE FROM t1
    WHERE s11 > ANY
     (SELECT COUNT(*) /* no hint */ FROM t2
      WHERE NOT EXISTS
       (SELECT * FROM t3
        WHERE ROW(5*t2.s1,77)=
         (SELECT 50,11*s1 FROM t4 UNION SELECT 50,77 FROM
          (SELECT * FROM t5) AS t5)));

    https://dev.mysql.com/doc/refman/5.7/en/subqueries.html

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  • 原文地址:https://www.cnblogs.com/wonchaofan/p/13521138.html
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