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git00ll
V2EX  ›  MySQL

mysql distinct 多列情况下,得到的结果是相当于将多列拼接在一起去重吗

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  •   git00ll · Dec 30, 2021 · 2303 views
    This topic created in 1627 days ago, the information mentioned may be changed or developed.

    是不是 约等于将选中的多列按照字符串拼接后去重. 不太理解 distinct 多列背后的逻辑

    2 replies    2021-12-30 14:51:51 +08:00
    Tsukihime
        1
    Tsukihime  
       Dec 30, 2021   ❤️ 1
    In most cases, a DISTINCT clause can be considered as a special case of GROUP BY.

    https://dev.mysql.com/doc/refman/8.0/en/distinct-optimization.html
    breadenglish
        2
    breadenglish  
       Dec 30, 2021   ❤️ 1
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