Question

SQL的新手，给我带来了以下问题。很抱歉，这是一个简单的解决方法。我今天早上看的所有替换问题似乎都不能解决这个确切的问题。

我正在使用SQL Server 2017，并且具有类似于以下内容的表，实际表为100k +行，但遵循这种格式，它只包含更多的单独项和列：

ColA    ColB    ColC    ColD    ColE    ColF
----    ----    ----    ----    ----    ----
ROW1    Item1   2341    Null    Null    Null
ROW2    Item2   7953    Null    Null    Null
ROW3    Item1   Null    2342    Null    Null
ROW4    Item2   Null    9827    Null    Null
ROW5    Item1   Null    Null    1945    Null
ROW6    Item2   Null    Null    0745    Null
ROW7    Item1   Null    Null    Null    1298
ROW8    Item2   Null    Null    Null    2356

是否可以通过编程方式更新表，以使ROW1和ROW2具有D，E和F列的所有非NULL值？

Answer 1

这2条语句应该可以帮助您。如果仅在SELECT语句之后，则第一个是您要执行的语句。如果您想实际UPDATE的所有行，那么您需要具有CTE的行：

USE Sandbox;
GO

CREATE TABLE dbo.Tab (ColA char(4),
                      ColB char(5),
                      ColC char(5),
                      ColD char(5),
                      ColE char(5),
                      ColF char(5));
INSERT INTO dbo.Tab (ColA,
                     ColB,
                     ColC,
                     ColD,
                     ColE,
                     ColF)
VALUES('ROW1','Item1',2341,Null,Null,Null),
      ('ROW2','Item2',7953,Null,Null,Null),
      ('ROW3','Item1',Null,2342,Null,Null),
      ('ROW4','Item2',Null,9827,Null,Null),
      ('ROW5','Item1',Null,Null,1945,Null),
      ('ROW6','Item2',Null,Null,0745,Null),
      ('ROW7','Item1',Null,Null,Null,1298),
      ('ROW8','Item2',Null,Null,Null,2356);
GO

SELECT ColA,
       ColB,
       MAX(ColC) OVER (PARTITION BY ColB) AS ColC,
       MAX(ColD) OVER (PARTITION BY ColB) AS ColD,
       MAX(ColE) OVER (PARTITION BY ColB) AS ColE,
       MAX(ColF) OVER (PARTITION BY ColB) AS ColF
FROM dbo.Tab
ORDER BY ColB;
GO

WITH CTE AS(
    SELECT ColA,
           ColB,
           ColC,
           ColD,
           ColE,
           ColF,
           MAX(ColC) OVER (PARTITION BY ColB) AS ColCn,
           MAX(ColD) OVER (PARTITION BY ColB) AS ColDn,
           MAX(ColE) OVER (PARTITION BY ColB) AS ColEn,
           MAX(ColF) OVER (PARTITION BY ColB) AS ColFn
    FROM dbo.Tab)
UPDATE CTE
SET ColC = ColCn,
    ColD = ColDn,
    ColE = ColEn,
    ColF = ColFn;
GO

SELECT *
FROM Tab;

GO

DROP TABLE dbo.Tab;

SQL语句/存储过程替换单个表中的NULL值

1 个答案: