sql substr ช่วยทีนะคะ อยากทราบว่า ถ้าจะเขียน sql substring ตัดข้ออความ ที่มีตำแหน่งไม่แน่นอน

--FOR MSSQL

SELECT
    CASE
       WHEN CHARINDEX('/' ,[ANY_SUPPORT_CHARACTOR_FIELD]) > 1 THEN 
          SUBSTRING( [ANY_SUPPORT_CHARACTOR_FIELD],1
             ,CHARINDEX('/' ,[ANY_SUPPORT_CHARACTOR_FIELD])-1)
       ELSE NULL 
    END AS STRING_BEFORE_SLASH
FROM [ANY_TABLE_NAME]
WHERE ......

--FOR MSSQL
SELECT *
FROM
(
   SELECT
      CASE
          WHEN CHARINDEX('/' ,[ANY_SUPPORT_CHARACTOR_FIELD]) > 1 THEN 
             SUBSTRING( [ANY_SUPPORT_CHARACTOR_FIELD],1
                ,CHARINDEX('/' ,[ANY_SUPPORT_CHARACTOR_FIELD])-1)
             ELSE NULL 
       END AS STRING_BEFORE_SLASH
   FROM [ANY_TABLE_NAME]
) AS PRIMARY_QUERY
GROUP BY STRING_BEFORE_SLASH

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

-- =============================================
-- Author:		<Author,,Name>
-- Create date: <Create Date, ,>
-- Description:	<Description, ,>
-- =============================================
CREATE FUNCTION [dbo].[GETSTR_BEFORE_SOMTHNIG]
(
	@VarStrTofind AS NVARCHAR(MAX) ,@VarSource AS NVARCHAR(MAX)
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
	-- Declare the return variable here
	DECLARE 
		@CUTTING_POSITION		AS INT ,
		@RET_STR				AS NVARCHAR(MAX);

	-- Add the T-SQL statements to compute the return value here
	SET @CUTTING_POSITION = CHARINDEX(@VarStrTofind ,@VarSource);
	IF @CUTTING_POSITION <= 1 
	BEGIN
	   SET @RET_STR = SUBSTRING(@VarSource ,1 ,@CUTTING_POSITION -1);
	END 
	ELSE
	BEGIN
		SET @RET_STR ='' ;
	END

	-- Return the result of the function
	RETURN @RET_STR ;

END

GO

select GETSTR_BEFORE_SOMTHNIG('/' , number) as number
   ,date, sum(amount) as amount 
from chqout 
where (number between '111' and '222') 
   and (number like '[0-9]%') 
group by GETSTR_BEFORE_SOMTHNIG('/', number)
   ,paymentdate