SQL IF ELSE STATEMENT

Question

1. SELECT ORDER
FROM ORDERLIST
WHERE IsCompleted='Y'

2. SELECT ORDER
FROM ORDERLIST
WHERE IsCompleted='N'

然后输出是＆＃39; NULL＆＃39;

我想整合这两个逻辑，但我不知道如何使代码工作。请帮帮我！

Answer 1

试试这个......

您可以使用CASE WHEN表达式

SELECT 
    CASE
        WHEN IsCompleted='Y' 
        THEN
            [ORDER]
        ELSE WHEN IsCompleted='N' 
        THEN
           NULL
    END 
FROM 
    ORDERLIST 

Answer 2

＆＃39;分类：G642.44＆＃39;如UNION？：

SELECT ORDER
FROM ORDERLIST
WHERE IsCompleted='Y'
UNION
SELECT NULL
FROM ORDERLIST
WHERE IsCompleted='N'

Answer 3

试试这个，这应该可以让你在一个表中得到所有结果。

    SELECT ORDER
    FROM ORDERLIST
    WHERE IsCompleted = 'Y' OR IsCompleted = 'N'