sql - Case 表达式只能嵌套到第 10 层

Question

我有以下代码用于处理电话号码，例如澳大利亚的国家代码+61、61、001161等。我无法再在以下位置插入任何 CASE 语句:CASE WHEN LEFT(@BPartyNo, 4) = '+610'

它说Case表达式只能嵌套到第10层

如何简化此 TSQL，以便可以放置更多 CASE？

USE [TelcoStage_PROD]
GO
/****** Object:  UserDefinedFunction [dbo].[ufn_stg_ProperBPartyNoExtra]    Script Date: 07/12/2010 15:27:52 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

--=====================================================================================================================
-- OBJECT NAME          : dbo.ufn_stg_ProperBPartyNoExtra
-- INPUTS               : @BPartyNo 
-- OUTPUTS              : VARCHAR(32)
-- RETURN CODES         : N/A
-- DEPENDENCIES         : N/A
-- DESCRIPTION          : This function is used to get the extra after 10 character (MNET or S)
--
-- EXAMPLES (optional)  : N/A
--
-- HISTORY:
-- #-----------------------------------------------------------------------------------------------------------------
-- # DATE       | VERSION        | MODIFIED BY | DESCRIPTION
-- #-----------------------------------------------------------------------------------------------------------------
====================================================================================================================


ALTER FUNCTION [dbo].[ufn_stg_ProperBPartyNoExtra](@BPartyNo AS VARCHAR(MAX))RETURNS VARCHAR(32)
AS
BEGIN   
    DECLARE @Return VARCHAR(32);

    SET @Return = '';

    IF (LEN(@BPartyNo) > 0) 
        SELECT @Return = CASE WHEN LEFT(@BPartyNo, 4) = '+610' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 5, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 5, LEN(@BPartyNo)) ) ) ELSE
                                    CASE WHEN LEFT(@BPartyNo, 3) = '+61' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 4, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 4, LEN(@BPartyNo)) ) ) ELSE
                                        CASE WHEN LEFT(@BPartyNo, 2) = '61' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 3, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 3, LEN(@BPartyNo)) ) ) ELSE       
                                            CASE WHEN LEFT(@BPartyNo, 6) = '001161' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 7, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 7, LEN(@BPartyNo)) ) ) ELSE 
                                                CASE WHEN ( LEFT(@BPartyNo,2) = '01' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo)) ELSE 
                                                    CASE WHEN ( LEFT(@BPartyNo,2) = '02' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo)) ELSE 
                                                        CASE WHEN ( LEFT(@BPartyNo,2) = '03' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo)) ELSE 
                                                            CASE WHEN ( LEFT(@BPartyNo,2) = '04' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo)) ELSE 
                                                                CASE WHEN ( LEFT(@BPartyNo,2) = '07' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo)) ELSE 
                                                                    CASE WHEN ( LEFT(@BPartyNo,2) = '08' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo)) ELSE '' END
                                                                END
                                                            END
                                                        END
                                                    END
                                                END
                                            END
                                        END
                                    END
                        END;
    ELSE
        SELECT @Return = '';

    RETURN @Return
END

Answer 1

它们根本不需要嵌套:

   SELECT @Return = CASE WHEN LEFT(@BPartyNo, 4) = '+610' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 5, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 5, LEN(@BPartyNo)) ) )
                         WHEN LEFT(@BPartyNo, 3) = '+61' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 4, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 4, LEN(@BPartyNo)) ) )
                         WHEN LEFT(@BPartyNo, 2) = '61' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 3, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 3, LEN(@BPartyNo)) ) )
                         WHEN LEFT(@BPartyNo, 6) = '001161' THEN SUBSTRING('0' + SUBSTRING(@BPartyNo, 7, LEN(@BPartyNo)), 11, LEN( '0' + SUBSTRING(@BPartyNo, 7, LEN(@BPartyNo)) ) )
                         WHEN ( LEFT(@BPartyNo,2) = '01' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo))
                         WHEN ( LEFT(@BPartyNo,2) = '02' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo))
                         WHEN ( LEFT(@BPartyNo,2) = '03' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo))
                         WHEN ( LEFT(@BPartyNo,2) = '04' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo))
                         WHEN ( LEFT(@BPartyNo,2) = '07' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo))
                         WHEN ( LEFT(@BPartyNo,2) = '08' AND LEN(@BPartyNo) > 10 ) THEN SUBSTRING(@BPartyNo, 11, LEN(@BPartyNo))
                         ELSE ''
                     END

就我个人而言，我会重组您的代码，以便确保数据在输入时得到清理，而不是现在尝试对其进行清理(显然为时已晚......)。或者至少以您的客户端语言进行转换(即以任何调用此存储过程的方式)，这有望比 T-SQL 更适合字符串操作的任务。