我的目标是删除我的表中不是分组CaseKey的MAX(recordDate)的所有记录.所以如果我有9个记录,3组3个小组,每个casekey有3个日期.我会删除每组的2个较低的日期,并提供3个总记录,只剩下每个记录的MAX(recordDate).

我有以下SQL查询：

DELETE FROM table
    WHERE tableID NOT IN (
    SELECT tableID
    FROM (
    Select MAX(recordDate) As myDate,tableID From table
    Group By CaseKey
    ) As foo
    )

我收到错误：
第3行错误…列’table.tableID’在选择列表中无效,因为它不包含在聚合函数或GROUP BY子句中.

显然,我可以将tableID添加到我的Group By子句,但是该语句的结果不正确,并返回所有行,而不是返回分组CaseKey的MAX recordDate.

服务器现在正在关闭,但明显的答案是：(从WildPlasser的答案微小的调整)

DELETE zt FROM ztable zt
WHERE EXISTS (
    SELECT * FROM ztable ex
    WHERE ex.CaseKey = zt.CaseKey
    AND ex.recordDate > zt.recordDate
);

换句话说,对于zt中的每个记录,运行一个查询来查看同一个记录是否还有一个记录与更高的recordDate.如果是,则WHERE EXISTS语句通过并且记录被删除,否则WHERE语句失败,并且该记录是其自己的MAX recordDate.

谢谢WildPlasser,为了这种简单化的方法,我以某种方式吹起来.

DELETE FROM ztable zt
WHERE EXISTS (
    SELECT *
    FROM ztable ex
    WHERE ex.CaseKey = zt.CaseKey
    AND ex.recordDate > zt.recordDate
    );

DELETE FROM ztable zt
WHERE EXISTS (
    SELECT *
    FROM ztable ex
    WHERE ex.CaseKey = zt.CaseKey
    AND (   ex.recordDate > zt.recordDate
        OR (ex.recordDate = zt.recordDate AND ex.TableId > zt.TableId)
        )
    );