BEGIN TRANSACTION

DECLARE @Today DATETIME
SET @Today = GETDATE()

DECLARE @Temp TABLE
    (
      ID INT ,
      [val1] [varchar](50) ,
      [val2] [varchar](50) ,
      [val3] [varchar](50) ,
      [entryDate] [datetime]
    )

INSERT  INTO [dbo].[TableA]
        ( val1 ,
          val2 ,
          val3 ,
          entryDate
        )
OUTPUT  INSERTED.ID ,
        INSERTED.val1 ,
        INSERTED.val2 ,
        INSERTED.val3 ,
        INSERTED.entryDate
        INTO @Temp
        SELECT  val1 ,
                val2 ,
                val3 ,
                entryDate
        FROM    [dbo].[TableC]

INSERT  INTO [dbo].[TableB]
        ( TableAID ,
          comID ,
          RelationshipID ,
          xPercent ,
          [status] ,
          dateBegin
        )
        SELECT  T.ID AS TableAID ,
                C.comID AS comID ,
                1 AS RelationshipID ,
                '100.00' AS xPercent ,
                1 AS [status] ,
                @Today AS dateBegin
        FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY val1 ASC, val2 ASC, val3 ASC, entryDate ASC ) AS RowNumber ,
                            ID
                  FROM      @Temp
                ) AS T
                INNER JOIN ( SELECT ROW_NUMBER() OVER ( ORDER BY val1 ASC, val2 ASC, val3 ASC, entryDate ASC ) AS RowNumber ,
                                    comID
                             FROM   [dbo].[TableC]
                           ) AS C ON T.RowNumber = C.RowNumber

COMMIT TRANSACTION

merge into [table1] as t
using [external_table] as s
on 1=0 --modify this predicate as necessary
when not matched then insert (data)
values (s.[col1])
output inserted.id, s.[col2] into [table2]
;

MERGE TableA AS ta 
USING (SELECT c.val1 as val1, c.val2 as val2 , c.val3 as val3, c.comID as ComId FROM TableC C) AS tc
ON 
[color=#ff0033]
REPLACE(COALESCE(ta.val1,'')+ COALESCE(ta.val2,'')+COALESCE(ta.val3,''),' ','') 
= 
REPLACE(COALESCE(tc.val1,'')+ COALESCE(tc.val2,'')+COALESCE(tc.val3,''),' ','') 
[/color]
WHEN NOT MATCHED BY TARGET THEN
  INSERT (val1, val2, val3,entryDate) 
  VALUES (tc.val1, tc.val2, tc.val3,@Today)
OUTPUT INSERTED.ID ,tc.ComId ,1 As RelationshipID
,'100.00' As xPercent, 1 As [status],@Today As dateBegin 
INTO TableB (TableAID, comID, RelationshipID, xPercent, [status], dateBegin)
;