我该如何选择基于条件的列？(how do I select a column based on co

我有一个变量，名为@status我这个select语句之前设置：

Select
ordr_num as num,
ordr_date as date,
ordr_ship_with as shipwith
From
order
where ordr_num = @ordrNum

我只是想选择ordr_ship_with如果列@status <> 'Cancelled' ，否则我要选择空的shipwith。 如何做到这一点？

Answer 1:

SELECT ordr_num as num, ordr_date as date, 
    CASE WHEN @status<>'Cancelled' THEN ordr_ship_with ELSE NULL END as shipwith 
FROM order 
WHERE ordr_num = @ordrNum

Answer 2:

尝试了这一点

Select 
    ordr_num as num, 
    ordr_date as date, 
    CASE 
        WHEN @Status <> 'Cancelled' THEN ordr_ship_with 
        ELSE NULL END
    as shipwith 
From order 
where ordr_num = @ordrNum

虽然我有一种感觉，你状态处于Order表的实际列。 在这种情况下，这样做：

Select 
    ordr_num as num, 
    ordr_date as date, 
    CASE 
        WHEN Status <> 'Cancelled' THEN ordr_ship_with 
        ELSE NULL END
    as shipwith 
From order 
where ordr_num = @ordrNum

Answer 3:

Select
    ordr_num as num,
    ordr_date as date,
    CASE WHEN @status <> 'Cancelled' THEN ordr_ship_with ELSE NULL END as shipwith
From
    order where ordr_num = @ordrNum

Answer 4:

使用案例： http://msdn.microsoft.com/en-us/library/ms181765.aspx

Answer 5:

试试这个

SELECT CASE     
 WHEN @status <> 'cancelled' THEN ordr_ship_with  
 ELSE null  
END AS shipwith, ... other fields

文章来源: how do I select a column based on condition?