SQL Server 2008中删除重复

Question

我有重复这样

col1, col2 
1, alex 
1, alex 
2, liza 
2, liza 
3, peter 
3, peter 

只有每两个。我如何删除重复项？

Answer 1

WITH q AS 
     (
     SELECT *, 
       ROW_NUMBER() OVER (PARTITION BY col1, col2 ORDER BY col1, col2) AS rn 
     FROM mytable 
     ) 
DELETE 
FROM q 
WHERE rn >= 2 

在这里看到：

• Deleting duplicates

Answer 2

如果源表不是很大。

select distinct * from origin_table into temp_table; 
truncate table origin_table; 
insert into origin_table select * from temp_table ; 
drop table temp_table; 

Answer 3

insert into table_new 
    Select col1, col2, min(pk) as pk from table_old 
    group by col1, col2 

-- debug table_new 

drop table_old