如何删除除MySQL表中最新日期之外的所有重复行？

Question

  

可能重复：
  Remove duplicate rows from table with join

我的表看起来像这样：
a，b，c，d，date
除了包含最新a的行之外，如何删除具有相同b，c，d和date的所有行？ 有一些行，a和b相同，c和d不相同。

Answer 1

试试这个：

DELETE FROM tableName 
WHERE (a, b, c, d, dte) NOT IN (SELECT a, b, c, d, dte 
                                FROM (SELECT a, b, c, d, MAX(dte) dte 
                                     FROM tableName GROUP BY a, b, c, d
                                ) AS A );

选中此SQL FIDDLE DEMO

Answer 2

您可以像这样使用左表连接

DELETE table1
  FROM table1
  LEFT JOIN 
  ( SELECT MAX(`date`) as dates,a,b,c,d FROM table1
    GROUP BY a,b,c,d
  ) A
    ON table1.date = A.dates
   AND table1.a = A.a
   AND table1.b = A.b
   AND table1.c = A.c
   AND table1.d = A.d
 WHERE A.dates IS NULL;

See this SQLFiddle

有关详情，请参阅DELETE Syntax of MySQL