SELECT @rowid:=@rowid+1 as rowid
FROM table1, (SELECT @rowid:=0) as init
ORDER BY sorter_field
：也就是说，您将需要创建一个临时表，将测距子查询插入到该临时表中，并通过与临时表联接来从原始表中删除（您将需要一些唯一的行标识符）：
CREATE TEMPORARY TABLE duplicates ...
INSERT INTO duplicates (rowid, field1, field2, some_row_uid)
SELECT
@rowid:=IF(@f1=field1 AND @f2=field2, @rowid+1, 0) as rowid,
@f1:=field1 as field1,
@f2:=field2 as field2,
some_row_uid
FROM testruns t, (SELECT @rowid:=NULL, @f1:=NULL, @f2:=NULL) as init
ORDER BY field1, field2 DESC;
DELETE FROM my_table USING my_table JOIN duplicates
ON my_table.some_row_uid = duplicates.some_row_uid AND duplicates.rowid > 0
由于这是一次操作，因此不会带来太多开销。
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