如何從SQL Server中的表中刪除重複的行

Question

我有一個名爲table1的表具有重複值。它看起來像這樣：

new 
pen 
book 
pen 
like 
book 
book 
pen 

但我想從該表中刪除重複的行並將其插入到被稱爲table2另一個表。

table2應該是這樣的：

new 
pen 
book 
like 

我怎樣才能做到這一點在SQL Server？

Answer 1

假設領域被評爲name：

INSERT INTO table2 (name) 
SELECT name FROM table1 GROUP BY name 

該查詢會得到大家的唯一名稱。

你甚至可以把它們放在一個表變量，如果你想：

DECLARE @Table2 TABLE (name VARCHAR(50)) 

INSERT INTO @Table2 (name) 
SELECT name FROM table1 GROUP BY name 

或者你可以使用一個臨時表：

CREATE TABLE #Table2 (name VARCHAR(50)) 

INSERT INTO @Table2 (name) 
SELECT name FROM table1 GROUP BY name 

Answer 2

您可以用INSERT是SELECT就做這個很容易從CTE您使用ROW_NUMBER()，如：

DECLARE @YourTable table (YourColumn varchar(10)) 
DECLARE @YourTable2 table (YourColumn varchar(10)) 
INSERT INTO @YourTable VALUES ('new') 
INSERT INTO @YourTable VALUES ('pen') 
INSERT INTO @YourTable VALUES ('book') 
INSERT INTO @YourTable VALUES ('pen') 
INSERT INTO @YourTable VALUES ('like') 
INSERT INTO @YourTable VALUES ('book') 
INSERT INTO @YourTable VALUES ('book') 
INSERT INTO @YourTable VALUES ('pen') 

;WITH OrderedResults AS 
(
SELECT 
    YourColumn, ROW_NUMBER() OVER (PARTITION BY YourColumn ORDER BY YourColumn) AS RowNumber 
    FROM @YourTable 
) 
INSERT INTO @YourTable2 
     (YourColumn) 
    SELECT YourColumn FROM OrderedResults 
     WHERE RowNumber=1 

SELECT * FROM @ YourTable2

OUTPUT：

--this will just remove them from your original table 
DECLARE @YourTable table (YourColumn varchar(10)) 
INSERT INTO @YourTable VALUES ('new') 
INSERT INTO @YourTable VALUES ('pen') 
INSERT INTO @YourTable VALUES ('book') 
INSERT INTO @YourTable VALUES ('pen') 
INSERT INTO @YourTable VALUES ('like') 
INSERT INTO @YourTable VALUES ('book') 
INSERT INTO @YourTable VALUES ('book') 
INSERT INTO @YourTable VALUES ('pen') 

;WITH OrderedResults AS 
(
SELECT 
    YourColumn, ROW_NUMBER() OVER (PARTITION BY YourColumn ORDER BY YourColumn) AS RowNumber 
    FROM @YourTable 
) 
DELETE OrderedResults 
    WHERE RowNumber!=1 

SELECT * FROM @YourTable 

OUTPUT：

YourColumn 
---------- 
book 
like 
new 
pen 

(4 row(s) affected) 

您可以在CTE在您使用ROW_NUMBER()，就像一個DELETE做到這一點很容易

YourColumn 
---------- 
new 
pen 
book 
like 

(4 row(s) affected) 

Answer 3

我發佈了一些事情g幾個星期前通過使用DELETE TOP X來刪除重複項。顯然，僅對於一組重複項。然而在評論中，我被Joshua Patchak給了這個小小的寶石。

;WITH cte(rowNumber) AS 
(SELECT ROW_NUMBER() OVER (PARTITION BY [List of Natural Key Fields] 
ORDER BY [List of Order By Fields]) 
FROM dbo.TableName) 

DELETE FROM cte WHERE rowNumber>1 

這將擺脫表中的所有重複項。
如果你想閱讀討論，這裏是原文。 Duplicate rows in a table.