SQL 服务器中的 TrimEnd 等价物

Question

我有列（数字），其值如下：

1,2,3
1,2,3,
1,2,3,,,
1,2,3,,,,,,

我想 Trim 字符串末尾的所有逗号，所以结果将是

1,2,3
1,2,3
1,2,3
1,2,3

我试过下面的查询，但这样我们只能删除最后一个逗号

DECLARE @String as VARCHAR(50)
SET @String='1,2,3,4,,,,,,,,,,,,,,,,'

SELECT CASE WHEN right(rtrim(@String),1) = ',' then substring(rtrim(@String),1,len(rtrim(@String))-1)
    ELSE @String 
    END AS TruncString

如何删除字符串末尾的所有逗号？

Answer 1

因为多次出现，您不能使用简单的内置函数表达式来完成，但简单的用户定义函数可以完成这项工作。

create function dbo.MyTrim(@text varchar(max)) returns varchar(max)
as
-- function to remove all commas from the right end of the input.
begin

    while (right(@text, 1) = ','
    begin
        set @text = left(@text, len(@text) - 1)
    end

    return @text

end
go

Answer 2

您可以搜索第一次出现的 ',,' 并获取之前的所有内容：

select (case when numbers like '%,,'
             then left(numbers, charindex(',,', numbers) - 1)
             when numbers like '%,'
             then left(numbers, len(numbers) - 1)
             else numbers
        end)

注意：您似乎是在以逗号分隔的字符串中存储事物列表。通常最好使用联结 table.

来存储它们

编辑：

或者，另一种没有 case 的表述方式：

select left(numbers + ',,', charindex(',,', numbers + ',,') - 1)

Answer 3

您可以使用：

LEFT(Numbers, LEN(Numbers) - (PATINDEX('%[^,]%', REVERSE(Numbers)) - 1))

这样做的前提是你先用REVERSE反转字符串：

REVERSE(Numbers) --> ,,,,,,3,2,1

然后使用 PATINDEX 和模式匹配 [^,]:

找到第一个不是逗号的字符的位置

PATINDEX('%[^,]%', REVERSE(Numbers)) --> ,,,,,,3,2,1 = 7

然后就可以使用LEN, to get the inverse position, i.e. if the position of the first character that is not a comma is 7 in the reversed string, and the length of the string is 10, then you need the first 4 characters of the string. You then use SUBSTRING的字符串长度来提取相关部分

一个完整的例子是

SELECT  Numbers,
        Reversed = REVERSE(Numbers),
        Position = PATINDEX('%[^,]%', REVERSE(Numbers)),
        TrimEnd = LEFT(Numbers, LEN(Numbers) - (PATINDEX('%[^,]%', REVERSE(Numbers)) - 1))
FROM    (VALUES 
            ('1,2,3'), 
            ('1,2,3,'), 
            ('1,2,3,,,'), 
            ('1,2,3,,,,,,'), 
            ('1,2,3,,,5,,,'), 
            (',,1,2,3,,,5,,')
        ) t (Numbers);

编辑

为了响应编辑，在语法上有一些错误，下面有函数 trim 开始，trim 逗号两边：

SELECT  Numbers,
        Reversed = REVERSE(Numbers),
        Position = PATINDEX('%[^,]%', REVERSE(Numbers)),
        TrimEnd = LEFT(Numbers, LEN(Numbers) - (PATINDEX('%[^,]%', REVERSE(Numbers)) - 1)),
        TrimStart = SUBSTRING(Numbers, PATINDEX('%[^,]%', Numbers), LEN(Numbers)),
        TrimBothSide = SUBSTRING(Numbers, 
                                    PATINDEX('%[^,]%', Numbers), 
                                    LEN(Numbers) - 
                                        (PATINDEX('%[^,]%', REVERSE(Numbers)) - 1) - 
                                        (PATINDEX('%[^,]%', Numbers) - 1)
                                    )
FROM    (VALUES 
            ('1,2,3'), 
            ('1,2,3,'), 
            ('1,2,3,,,'), 
            ('1,2,3,,,,,,'), 
            ('1,2,3,,,5,,,'), 
            (',,1,2,3,,,5,,')
        ) t (Numbers);

Answer 4

运行下面查询得到预期结果

declare @sql varchar(500)

set @sql ='1,2,3,,,,,,'

select left(@sql,case charindex(',,',@sql,0)
when 0 then len(@sql)-1
else charindex(',,',@sql,0)-1
end)

Answer 5

Create FUNCTION TrimStartEndAll 
(
    @string varchar(max),
    @trimValue varchar(5),
    @removeall int=0 
)

RETURNS varchar(max)
AS
BEGIN

    if @removeall=1
    while  CHARINDEX(@trimValue,@string) >0 and @removeall=1
    begin
        set @string = REPLACE(@string,@trimValue,'')
    end
    if @removeall = 0
        begin

             while  CHARINDEX(@trimValue,@string) =1
                begin
                    set @string = SUBSTRING(@string,len(@trimValue)+1, len(@string))
                end

             while  substring(@string,len(@string)-len(@trimValue)+1, len(@trimValue)) = @trimValue
                begin
                    set @string =substring(@string,0, (len(@string)-len(@trimValue)+1))
                end
         end
    return @string
END
GO

输出

select dbo.TrimStartEndAll( ',,1,2,3,,,5,,,,,,,,,',',,',1) => 1,2,3,5,
select dbo.TrimStartEndAll( ',,1,2,3,,,5,,,,,,,,,',',,',0) => 1,2,3,,,5,

Answer 6

SQL Server 2017实现了TRIM功能的增强版。您可以使用 TRIM(',' FROM '1,2,3,') 获取字符串 '1,2,3'

SQL 服务器中的 TrimEnd 等价物

TrimEnd Equivalent in SQL Server

sql

trim

sql-server-2008