删除SQL Server 2010中的"重复"行

Question

我在批量插入脚本中犯了一个错误,所以现在我有不同colX的"重复"行.我需要删除这些重复的行,但我无法弄清楚如何.更确切地说,我有这个:

 col1 | col2 | col3 | colX      
----+----------------------
  0   |  1   |  2   |  a
  0   |  1   |  2   |  b
  0   |  1   |  2   |  c
  0   |  1   |  2   |  a
  3   |  4   |  5   |  x
  3   |  4   |  5   |  y
  3   |  4   |  5   |  x
  3   |  4   |  5   |  z

我想保留每个(row,colX)的第一次出现:

 col1 | col2 | col3 | colX      
----+----------------------
  0   |  1   |  2   |  a
  3   |  4   |  5   |  x

谢谢您的回复 :)

Answer 1

尝试使用Sql Server的CTE最简单的方法:http://www.sqlfiddle.com/#!3/2d386 /2

数据:

CREATE TABLE tbl
    ([col1] int, [col2] int, [col3] int, [colX] varchar(1));

INSERT INTO tbl
    ([col1], [col2], [col3], [colX])
VALUES
    (0, 1, 2, 'a'),
    (0, 1, 2, 'b'),
    (0, 1, 2, 'c'),
    (0, 1, 2, 'a'),
    (3, 4, 5, 'x'),
    (3, 4, 5, 'y'),
    (3, 4, 5, 'x'),
    (3, 4, 5, 'z');

解:

select * from tbl;

with a as
(
  select row_number() over(partition by col1 order by col2, col3, colX) as rn 
  from tbl   
)
delete from a where rn > 1;

select * from tbl;

输出:

| COL1 | COL2 | COL3 | COLX |
-----------------------------
|    0 |    1 |    2 |    a |
|    0 |    1 |    2 |    b |
|    0 |    1 |    2 |    c |
|    0 |    1 |    2 |    a |
|    3 |    4 |    5 |    x |
|    3 |    4 |    5 |    y |
|    3 |    4 |    5 |    x |
|    3 |    4 |    5 |    z |


| COL1 | COL2 | COL3 | COLX |
-----------------------------
|    0 |    1 |    2 |    a |
|    3 |    4 |    5 |    x |

或许这个:http://www.sqlfiddle.com/#!3/af826/1

数据:

CREATE TABLE tbl
    ([col1] int, [col2] int, [col3] int, [colX] varchar(1));

INSERT INTO tbl
    ([col1], [col2], [col3], [colX])
VALUES
    (0, 1, 2, 'a'),
    (0, 1, 2, 'b'),
    (0, 1, 2, 'c'),
    (0, 1, 2, 'a'),
    (0, 1, 3, 'a'),
    (3, 4, 5, 'x'),
    (3, 4, 5, 'y'),
    (3, 4, 5, 'x'),
    (3, 4, 5, 'z');

解:

select * from tbl;


with a as
(
    select row_number() over(partition by col1, col2, col3 order by colX) as rn 
    from tbl   
)
delete from a where rn > 1;

select * from tbl;

输出:

| COL1 | COL2 | COL3 | COLX |
-----------------------------
|    0 |    1 |    2 |    a |
|    0 |    1 |    2 |    b |
|    0 |    1 |    2 |    c |
|    0 |    1 |    2 |    a |
|    0 |    1 |    3 |    a |
|    3 |    4 |    5 |    x |
|    3 |    4 |    5 |    y |
|    3 |    4 |    5 |    x |
|    3 |    4 |    5 |    z |

| COL1 | COL2 | COL3 | COLX |
-----------------------------
|    0 |    1 |    2 |    a |
|    0 |    1 |    3 |    a |
|    3 |    4 |    5 |    x |