如何将包含唯一标识符列表的 varchar 转换为 SQL 服务器中的唯一标识符列表

Question

查询中employeeId列的数据类型为uniqueidentifier。执行时出现以下错误

Conversion failed when converting from a character string to uniqueidentifier.

declare @tt nvarchar = 'e347d817-3121-e811-9c0b-58fb847a6047,e447d817-3121-e811-9c0b-58fb847a6047,e147d817-3121-e811-9c0b-58fb847a6047,df47d817-3121-e811-9c0b-58fb847a6047,de47d817-3121-e811-9c0b-58fb847a6047,e547d817-3121-e811-9c0b-58fb847a6047,e247d817-3121-e811-9c0b-58fb847a6047,e047d817-3121-e811-9c0b-58fb847a6047,dd47d817-3121-e811-9c0b-58fb847a6047'

select * 
from [dbo].[employee] 
where [employeeId] in (@tt)

如何将唯一标识符 (GUID) 字符串转换为唯一标识符列表？

我曾尝试按照中所示执行转换但是没用。

Answer 1

嗯，如果你这样声明你的变量：

declare @tt nvarchar

您得到一串长度正好是一个字符的字符串！

您应该始终（没有例外！）为您的[定义明确的长度 =14=]（和nvarchar）变量：

declare @tt nvarchar(2000) = .....

此外 - 如果您将 nvarchar 定义为 Unicode 字符串，您必须在您分配给它的字符串文字前加上 N它是一个 Unicode 字符串文字：

declare @tt nvarchar(2000) = N'.......'

但最终，即使这样 也不会 起作用 - 因为 IN 运算符需要一个列表 - 不是单个字符串.....您应该声明一个 table 变量，将您的值插入该 table 变量，然后执行 select:

DECLARE @tt TABLE (ID UNIQUEIDENTIFIER)

INSERT INTO @tt(ID)
VALUES ('e347d817-3121-e811-9c0b-58fb847a6047'), 
       ('e447d817-3121-e811-9c0b-58fb847a6047'),
       etc. 

SELECT * 
FROM [dbo].[employee] 
WHERE [employeeId] IN (SELECT ID FROM @tt)

Answer 2

您需要动态 SQL 来实现：

--declare string, that will hold your query
declare @query varchar(4000) = 'select * 
                                from [dbo].[employee] 
                                where [employeeId] in '
--transform your list of IDs to list of values suitable for a where clause
set @tt = '(''' + replace(@tt, ',', ''',''') + ''')'
set @query = @query + @tt
--execute the query
exec(@query)

Answer 3

--Create this function.  This function will convert string to Id as row
CREATE FUNCTION [dbo].[StrParse]
               (@delimiter CHAR(1),  
                @csv       NTEXT)  
RETURNS @tbl TABLE(Keys  NVARCHAR(255))  
AS  

  BEGIN  
    DECLARE  @len INT  
    SET @len = Datalength(@csv)  
    IF NOT @len > 0  
      RETURN  

    DECLARE  @l INT  
    DECLARE  @m INT  

    SET @l = 0  
    SET @m = 0  

    DECLARE  @s VARCHAR(255)  
    DECLARE  @slen INT  

    WHILE @l <= @len  
      BEGIN  

        SET @l = @m + 1--current position  
        SET @m = Charindex(@delimiter,Substring(@csv,@l + 1,255))--next delimiter or 0  

        IF @m <> 0  
          SET @m = @m + @l  
        --insert @tbl(keys) values(@m)  
        SELECT @slen = CASE   
                         WHEN @m = 0 THEN 255 --returns the remainder of the string  
                         ELSE @m - @l  
                       END --returns number of characters up to next delimiter  

        IF @slen > 0  
          BEGIN  
            SET @s = Substring(@csv,@l,@slen)  
            INSERT INTO @tbl  
                       (Keys)  
            SELECT @s  
          END  

        SELECT @l = CASE   
                      WHEN @m = 0 THEN @len + 1 --breaks the loop  
                      ELSE @m + 1  
                    END --sets current position to 1 after next delimiter  
      END  

    RETURN  
  END
go

--Below code will return the value you are expecting
declare @tt nvarchar (MAX) = 'e347d817-3121-e811-9c0b-58fb847a6047,e447d817-3121-e811-9c0b-58fb847a6047'
select * 
from [dbo].[employee]
where [employeeId] in (select keys from dbo.StrParse (',', @tt))

如何将包含唯一标识符列表的 varchar 转换为 SQL 服务器中的唯一标识符列表

How to convert varchar containing list of uniqueidentifiers into a list of uniqueidentifiers in SQL Server

sql

sql-server

sql-server-2017