Question

我正在尝试删除在特定列中与另一行具有相同值的重复行。

输入

Shape      Color    Size   Location
ball       blue     small   s
circle     green    small   n
triangle   yellow   large   w
triangle   red      medium  n
circle     purple   small   n
ball       orange   small   s
square     green    medium  e

输出

Shape      Color    Size    Location
ball       blue     small    s
circle     green    small    n
triangle   yellow   large    w
triangle   red      medium   n
square     green    medium   e

基本上我想摆脱多余的行，其中1,3,4列的值与另一行的值相同

您可以使用窗口功能吗？

Answer 1

您可以尝试此查询。编写一个子查询，并将Row_Number与 windows函数一起使用。

select * 
from (
    SELECT *,ROW_NUMBER() OVER(PARTITION BY Shape,Size ORDER BY Shape) rn
    FROM T
) t1
WHERE t1.rn =1

sqlfiddle

Answer 2

如果您不关心返回哪种颜色，则可以执行此操作。此代码使用CTE添加行号，然后提取每个唯一Shape + Size + Location的第一条记录，并采用顶部的Color记录：

; WITH AllRecords
AS (
    SELECT
        Shape
        , Color
        , Size
        , Location
        , RowNum = ROW_NUMBER() OVER(PARTITION BY Shape, Size, Location ORDER BY Color)
    FROM YourTable
    )
SELECT *
FROM AllRecords
WHERE AllRecords.RowNum = 1;

Answer 3

您只需要添加group by子句。

select shape,size,color,location 
from t 
group by shape,size,color,location

Answer 4

如果我正确阅读了您的问题，则想从表中删除重复的值。是的，Windows函数是执行此操作的更有效方法之一。

DECLARE @Input TABLE 
(
  Shape varchar(20),
  Color varchar(20),
  Size varchar(20),
  Location char(1)
);

INSERT INTO @Input
VALUES
('ball'       ,'blue'     ,'small'   ,'s'),
('circle'     ,'green'    ,'small'   ,'n'),
('triangle'   ,'yellow'   ,'large'   ,'w'),
('triangle'   ,'red'      ,'medium'  ,'n'),
('circle'     ,'purple'   ,'small'   ,'n'),
('ball'       ,'orange'   ,'small'   ,'s'),
('square'     ,'green'    ,'medium'  ,'e');


WITH cte AS
(
  SELECT 
    ROW_NUMBER() OVER (PARTITION BY Shape, Size, Location ORDER BY (SELECT 0)) AS RowNum,
    Shape,
    Size,
    Location
  FROM @Input
)
DELETE 
FROM cte 
WHERE RowNum > 1;

SELECT
  *
FROM
  @Input;

--Output
+----------+--------+--------+----------+
|  Shape   | Color  |  Size  | Location |
+----------+--------+--------+----------+
| ball     | blue   | small  | s        |
| triangle | yellow | large  | w        |
| triangle | red    | medium | n        |
| circle   | purple | small  | n        |
| square   | green  | medium | e        |
+----------+--------+--------+----------+

SQL删除特定列中与另一行具有相同值的重复行

4 个答案: