Question

在我的SQL查询中，我试图在select子句中连接两个字符串。这是预期的结果：

col A   col B   Result
null    null    &
null    ''      &
null    XYZ     XYC
''      null    &
''      ''      &
''      XYZ     XYC
ABC     null    ABC
ABC     ''      ABC
ABC     XYZ     ABC-XYC

我的挑战是这样的 - 如何让“冲刺”出现在最后一个场景中，而不是其他场景？

这是我的尝试：

DECLARE @ColA as varchar(10)
DECLARE @ColB as varchar(10)

set @ColA = null; set @ColB = null;  select '&'   as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = null; set @ColB = '';    select '&'   as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = null; set @ColB = 'XYC'; select 'XYC' as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = '';   set @ColB = null;  select '&'   as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = '';   set @ColB = '';    select '&'   as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = '';   set @ColB = 'XYC'; select 'XYC' as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = 'ABC';set @ColB = null;  select 'ABC' as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = 'ABC';set @ColB = '';    select 'ABC' as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'
set @ColA = 'ABC';set @ColB = 'XYC'; select 'ABC-XYC' as 'Expected', COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&') as 'Actual'

你认为我什么时候必须做一个大案？我有很多像这样的专栏，这会让你无法忍受阅读。

谢谢！

更新：如果我使用了一个案例，那么我的选择看起来像这样，这似乎有效，但是会很痛苦。

select 
    case when (@ColA is not null and @ColA <> '') and
          (@ColB is not null and @ColB <> '') 
        then @ColA + '-' + @ColB
        else COALESCE(NULLIF(COALESCE(@ColA, '') + COALESCE(@ColB, ''), ''), '&')
    end

真的希望有人有一些改进的建议！

Answer 1

你能使用像这样的搜索案例函数吗？

Select Case When isnull(ColA, '') + isnull(ColB, '') == '' Then '&'
            When isnull(ColA, '') <> '' and isnull(ColB, '') <> '' Then ColA + '-' + ColB
            Else isnull(ColA, '') + isnull(ColB, '')
From Table1

Answer 2

我认为这个答案与其他答案并不完全不同，但你可以试试这个：

SELECT
CASE
    WHEN NULLIF(ColA,'') <> '' AND NULLIF(ColB,'') <> ''
        THEN ColA + '-' + ColB
    WHEN NULLIF(ColA,'') <> '' OR NULLIF(ColB,'') <> ''
        THEN COALESCE(ColA,ColB)
    ELSE '&'
END

sql server查询带有' - '的concat字符串

2 个答案: