Question

我需要从表的7个不同列连接，每列的文本之间用连字符。

在少数情况下列有空值，我得到字符串; --Account--stands---

所需的输出为Account-stands。请帮忙。

此致 Sajan

Answer 1

在SQL Server中，您可以执行以下操作：

select stuff(coalesce('-' + col1, '') +
             coalesce('-' + col2, '') +
             coalesce('-' + col3, '') +
             coalesce('-' + col4, '') +
             coalesce('-' + col5, '') +
             coalesce('-' + col6, '') +
             coalesce('-' + col7, ''),
              1, 1, '')

许多其他数据库支持像CONCAT_WS()这样的函数来简化此操作。

Answer 2

您可以使用COALESCE和STUFF来实现它，并避免出现空白值''的问题，您可以在后面添加NULLIF

select stuff( coalesce(nullif('-' + col1, '-'), '') +
              coalesce(nullif('-' + col2, '-'), '') +
              coalesce(nullif('-' + col3, '-'), '') +
              coalesce(nullif('-' + col4, '-'), '') +
              coalesce(nullif('-' + col5, '-'), '') +
              coalesce(nullif('-' + col6, '-'), '') +
              coalesce(nullif('-' + col7, '-'), ''),
              1, 1, '')

Answer 3

然后您可以使用CASE表达式来检查值是否为null。

<强>查询

select case when t.[concat_string] like '%-' 
then left(t.[concat_string], len(t.[concat_string]) - 1) 
else t.[concat_string] end as [concat_string] from(
    select 
    case when [col1] is null or ltrim(rtrim([col1])) = '' 
         then '' else [col1] + '-' end + 
    case when [col2] is null or ltrim(rtrim([col2])) = '' 
         then '' else [col2] + '-' end + 
    case when [col3] is null or ltrim(rtrim([col3])) = '' 
         then '' else [col3] + '-' end + 
    case when [col4] is null or ltrim(rtrim([col4])) = '' 
         then '' else [col4] + '-' end + 
    case when [col5] is null or ltrim(rtrim([col5])) = '' 
         then '' else [col5] + '-' end + 
    case when [col6] is null or ltrim(rtrim([col6])) = '' 
         then '' else [col6] + '-' end + 
    case when [col7] is null or ltrim(rtrim([col7])) = '' 
         then '' else [col7] end as [concat_string]
    from [your_table_name]
)t;

如果任何列不是VARCHAR，那么您可能需要CAST到VARCHAR

Answer 4

假设您已经构建了类似下面的查询。

select 
isnull(col1,'') + '-' + isnull(col2,'') + '-' + isnull(col3,'') as [columns]
from yourtable

用空格替换空值。例如，尝试以下查询

        select replace(replace ([columns],'|-',''), (case when 
charindex ('-|',replace ([columns],'|-','')) > 0 then '-|' else '|' end),'') 
    from(select 
        isnull(col1,'|') + '-' + isnull(col2,'|') + '-' +isnull(col3,'|')[columns]
        from yourtable)temp

Answer 5

DECLARE @String table (String nvarchar(max))
INSERT INTO @String
SELECT '--Account--stands---'

;WITH Cte
AS
(
SELECT String From
(
SELECT Split.a.value('.', 'VARCHAR(100)') AS String,
PATINDEX('%[a-zA-Z]%',Split.a.value('.', 'VARCHAR(100)')) AS ISChar FROM
(
SELECT 
 CAST( '<S>' + REPLACE(STRING ,'--','</S><S>') + '</S>' AS XML) AS String  from @String
 ) AS A
CROSS APPLY String.nodes('/S') AS Split(a)

) dt
Where dt.ISChar=1
)
SELECT DISTINCT STUFF((SELECT DISTINCT '- ' + String  FROM Cte
FOr xml path ('')),1,1,'') AS String
FROM Cte

输出

String
-------
 Account- stands

SQL Server：删除字符串开头和结尾的连字符

5 个答案: