Question

我有以下用于创建下表的SQL：

SELECT c.cOLUMN1 , c.cOLUMN2 , COALESCE (sc.cOLUMN3, 'XXX') AS cOLUMN3
FROM tabel AS c 


COLUMN1  COLUMN2   COLUMN3 

   1        1        XXX     
   1        1        26785  
   1        1        23432   
   1        1        XXX

我想添加两个新列 - 如果column3中的值也相等'XXX'那么新的列 NEWCOLUMN_A 应为“0”且 NEWCOLUM_B 应为“1”。

否则 NEWCOLUMN_A 中的新内容应为“1”， NEWCOLUM_B 应为“1”。

如下图所示：

COLUMN1  COLUMN2   COLUMN3  NEWCOLUMN_A  NEWCOLUMN_B
   1        1        XXX       0            1  
   1        1        26785     1            1           
   1        1        23432     1            1 
   1        1        XXX       0            1

Answer 1

SELECT 
    c.cOLUMN1 , 
    c.cOLUMN2 , 
    COALESCE (c.cOLUMN3, 'XXX') AS cOLUMN3,
    (CASE WHEN COALESCE(c.cOLUMN3, 'XXX') = 'XXX' THEN 0 ELSE 1 END) AS NEWCOLUMN_A,
    1 AS NEWCOLUMN_B
FROM tabel AS c

或者，由于第3列是派生的......

SELECT 
    c.cOLUMN1 , 
    c.cOLUMN2 , 
    COALESCE (c.cOLUMN3, 'XXX') AS cOLUMN3,
    (CASE WHEN c.cOLUMN3 IS NULL THEN 0 ELSE 1 END) AS NEWCOLUMN_A,
    1 AS NEWCOLUMN_B
FROM tabel AS c

Answer 2

首先将列添加到表中：

ALTER TABLE tabel
    ADD NEWCOLUMN_A BIT NULL;
ALTER TABLE tabel
    ADD NEWCOLUMN_B BIT NULL;

然后UPDATE表：

UPDATE tabel
SET NEWCOLUMN_A = CASE WHEN COLUMN3 = 'XXX' THEN 0 ELSE 1 END,
    NEWCOLUMN_B = 1

Answer 3

我认为这是你想要完成的事情。

Declare @string As nvarchar(50)
Set @string = 'xxx'
Select CASE WHEN @string  = 'xxx' Then 0 Else 1 End as NEWCOLUM_A, 1 as NEWCOLUM_B
set @string = 'yyy'
Select CASE WHEN @string  = 'xxx' Then 0 Else 1 End as NEWCOLUM_A, 1 as NEWCOLUM_B

Answer 4

SELECT c.cOLUMN1 
     , c.cOLUMN2 
     , COALESCE(c.cOLUMN3, 'XXX') AS cOLUMN3
     , CASE WHEN c.cOLUMN3 IS NULL THEN 1 ELSE 0 END AS NEWCOLUMN_A 
     , 1 AS NEWCOLUM_B 
FROM tabel AS c

在视图中向现有表添加新列

4 个答案: