delete t1
from table t1, table t2
where t1.columnA = t2.columnA
and t1.rowid>t2.rowid

邮政：

delete
from table t1
using table t2
where t1.columnA = t2.columnA
and t1.rowid > t2.rowid

哦,当然。使用临时表。如果你想要一个“工作”的单一的、性能不太好的语句，你可以使用:

DELETE FROM MyTable WHERE NOT RowID IN
    (SELECT 
        (SELECT TOP 1 RowID FROM MyTable mt2 
        WHERE mt2.Col1 = mt.Col1 
        AND mt2.Col2 = mt.Col2 
        AND mt2.Col3 = mt.Col3) 
    FROM MyTable mt)

基本上，对于表中的每一行，子选择将查找与所考虑行的完全相同的所有行的顶部RowID。因此，您最终会得到一个表示“原始”非重复行的RowIDs列表。

快速和脏删除精确重复的行(小表):

select  distinct * into t2 from t1;
delete from t1;
insert into t1 select *  from t2;
drop table t2;

如果您想预览要删除的行，并控制要保留的重复行。参见http://developer.azurewebsites.net/2014/09/better-sql-group-by-find-duplicate-data/

with MYCTE as (
  SELECT ROW_NUMBER() OVER (
    PARTITION BY DuplicateKey1
                ,DuplicateKey2 -- optional
    ORDER BY CreatedAt -- the first row among duplicates will be kept, other rows will be removed
  ) RN
  FROM MyTable
)
DELETE FROM MYCTE
WHERE RN > 1

另一种基于两列删除重复项的方法

我发现这个查询更容易阅读和替换。

DELETE 
FROM 
 TABLE_NAME 
 WHERE FIRST_COLUMNS 
 IN( 
       SELECT * FROM 
           ( SELECT MIN(FIRST_COLUMNS) 
             FROM TABLE_NAME 
             GROUP BY 
                      FIRST_COLUMNS,
                      SECOND_COLUMNS 
             HAVING COUNT(FIRST_COLUMNS) > 1 
            ) temp 
   )

注意:在运行查询之前最好模拟查询。

DELETE
FROM
    table_name T1
WHERE
    rowid > (
        SELECT
            min(rowid)
        FROM
            table_name T2
        WHERE
            T1.column_name = T2.column_name
    );