Error in Dynamic SQL

I Have Created the following SP to generate the Update Statements and it uses the table Col.TMap.T_Mp and the data in the table looks like:

ID  M_Type  ID_F     SF1      SF2
1   Acc     ACC_ID   AC_ID    NULL
1   STA     STA_ID   ST_ID    NULL
1   CHa     Cha_ID   CH_ID    NULL



CREATE PROCEDURE dbo.dtmap(
@ID INT
)
AS
BEGIN

DECLARE @SQL NVARCHAR(MAX)
DECLARE @SchemaName SYSNAME
DECLARE @TableName SYSNAME
DECLARE @DatabaseName SYSNAME
DECLARE @M_Type SYSNAME
DECLARE @SF1 VARCHAR(50)
DECLARE @SF2 VARCHAR(50)
DECLARE @ID_F VARCHAR(50)
DECLARE @BR CHAR(2)
SET @BR = CHAR(13) + CHAR(10)


DECLARE tickmapcur CURSOR FOR SELECT M_Type,ID_F,SF1,SF2
                              FROM Col.TMap.T_Mp
                              WHERE   [_ID] = @ID 



SELECT  @SchemaName = Source_Schema ,
        @TableName = Source_Table ,
        @DatabaseName = Source_Database
FROM    Manserv.dbo.S_Ds
WHERE   ID = @ID



OPEN   tickmapcur  

FETCH NEXT FROM tickmapcur INTO @M_Type,@ID_F,@SF1,@SF2

while @@fetch_status = 0

BEGIN


SET @SQL = 'SELECT SO1,
                   SO2,
                   ID
INTO ' + @M_Type + '_mtemp' + @BR + 'FROM ' + @M_Type + @BR
    + 'WHERE [ID] = ' + CAST(@ID AS NVARCHAR(10)) + @BR+ @BR


SET @SQL = @SQL + 'UPDATE  mt ' + @BR + 'SET ' + @ID_F+ ' = ac.' + @ID_F
    + @BR + 'FROM ' + @DatabaseName + '.' + @SchemaName + '.' + @TableName + ' t' + @BR 
    + 'LEFT OUTER JOIN '+ @M_Type + '_mtemp' 
    +' mtemp ON mtemp.ID = ' +  CAST(@ID AS NVARCHAR(10)) + @BR 
     + 'INNER JOIN ' + @M_Type + ' ac ON t.' + @SF1
    + COALESCE(mtemp.SO1, '') + ' SV1'
    + CASE WHEN @SF2 is NULL THEN '' ELSE COALESCE(@SF2, '')
    + COALESCE(mtemp.SO2, '') + ' SV2' END
    + 'AND ac.[ID] = ' + CAST(@ID AS NVARCHAR(10))
    + @BR + 'INNER JOIN ' + @DatabaseName + '.' + @SchemaName + '.'
    + @TableName + '_Dmtemp mt' + @BR
    + 'ON mt.[SRID] = t.[RID]  ' + @BR
    +@BR

FETCH NEXT FROM tickmapcur INTO @M_Type,@ID_F,@SF1,@SF2

PRINT ( @SQL )
END 

CLOSE tickmapcur
DEALLOCATE tickmapcur

END            

I get the following message:

Msg 4104, Level 16, State 1, Procedure dtmap, Line 57
The multi-part identifier "mtemp.SO1" could not be bound.
Msg 4104, Level 16, State 1, Procedure  dtmap, Line 57
The multi-part identifier "mtemp.SO1" could not be bound.

The output should be like this:

SELECT SO1,
       SO2,
       ID
INTO  ACC_Mtemp
FROM ACC
WHERE [ID] = @ID



UPDATE  mt 
SET ACC_ID = ac.ACC_ID
FROM Ms.AT.AT_CRAW t
LEFT OUTER JOIN ACC_Mtemp mtemp ON
mtemp.ID = @ID
INNER JOIN Acc ac ON t.AC_ID=SV1
AND ac.ID = 1
INNER JOIN Ms.AT.AT_CR开发者_开发百科AW_Dmtemp mt  mt
ON mt.[SRID] = t.[RID]

SELECT SO1,
       SO2,
       ID
INTO  STA_Mtemp
FROM STA
WHERE [ID] = @ID



UPDATE  mt 
SET STA_ID = ac.STA_ID
FROM Ms.AT.AT_CRAW t
LEFT OUTER JOIN STA_Mtemp mtemp ON
mtemp.ID = @ID
INNER JOIN STA ac ON t.ST_ID=SV1
AND ac.ID = 1
INNER JOIN Ms.AT.AT_CRAW_Dmtemp mt  mt
ON mt.[SRID] = t.[RID]


SELECT SO1,
       SO2,
       ID
INTO  CHa_Mtemp
FROM CHa
WHERE [ID] = @ID



UPDATE  mt 
SET CHa_ID = ac.CHa_ID
FROM Ms.AT.AT_CRAW t
LEFT OUTER JOIN CHa_Mtemp mtemp ON
mtemp.ID = @ID
INNER JOIN CHa ac ON t.CH_ID=SV1
AND ac.ID = 1
INNER JOIN Ms.AT.AT_CRAW_Dmtemp mt  mt
ON mt.[SRID] = t.[RID]

---

You are building the query incorrectly. ALL of the SQL parts need to be in quotes. The only thing outside of them should be the variables you are passing in.

---

You can't use the mtemp alias while you are creating the string. I suppose that you want to use it in the query instead:

+ ' COALESCE(mtemp.SO1, '''') SV1'

Same for mtemp.SO2 two lines down.

---

Looks like your missing a single quote before the COALESCE(mtemp.SO1, '') section.