[SQL Server 2005/2008]删除重复行(使用CTE公用表达式)

 

/* 创建测试数据, 7行中有3行是重复的.*/

CREATE TABLE DuplicateRcordTable (Col1 INT, Col2 INT)

INSERT INTO DuplicateRcordTable

SELECT 1, 1 UNION ALL

SELECT 1, 1 UNION ALL  --duplicate

SELECT 1, 1 UNION ALL  --duplicate

SELECT 1, 2 UNION ALL

SELECT 1, 2 UNION ALL  --duplicate

SELECT 1, 3 UNION ALL

SELECT 1, 4

GO  

 

/* 查询原始数据 */

SELECT * FROM DuplicateRcordTable

 

/* 创建公用表达式CTE, 按照表中所有字段分组，增加一列行序号 */

WITH CTE (COl1,Col2, DuplicateCount)

AS

(

SELECT COl1,Col2,

ROW_NUMBER() OVER(PARTITION BY COl1,Col2 ORDER BY Col1) AS DuplicateCount

FROM DuplicateRcordTable

)

/* 根据CTE，删除行序号中>1的行, 即重复的行 */

DELETE FROM CTE WHERE DuplicateCount > 1

GO  

 

/* 查询删除后的结果 */

SELECT * FROM DuplicateRcordTable

GO

drop table DuplicateRcordTable