Question

I have the below compare sql code.
Both tables contain a column IDCodeField.
How can I compare only IDCodeField, but return all fields if match IDCodeField?

Currently I am using below, however, it will compare all fields instead of IDCodeField only.

ALTER PROCEDURE [dbo].[usp_comparetables](@table1 varchar(100), 
 @table2 Varchar(100), @columnlist Varchar(1000))

AS

DECLARE @sql VARCHAR(8000)
SET @sql = 
'SELECT ''' + @table1 + ''' AS DataState, * FROM
    (SELECT ' + @columnlist + ' FROM ' + @table1 + '
        EXCEPT
    SELECT ' + @columnlist + ' FROM ' + @table2 + ') x
UNION
SELECT ''' + @table2 + ''' AS DataState, * from
    (SELECT ' + @columnlist + ' FROM ' + @table2 + '
        INTERSECT
    SELECT ' + @columnlist + ' FROM ' + @table1 +') x'

EXEC(@sql)

Used Answer:

DECLARE @sql VARCHAR(8000)
SET @sql = 
'SELECT ''' + @table1 + ''' AS DataState, '+@columnlist+' FROM ' + @table1 + ' where '+@compareparameter+' not in (select '+@compareparameter+' from '+@table2+') 
UNION ALL 
SELECT ''' + @table2 + ''' AS DataState, '+@columnlist+' FROM ' + @table2 + ' where '+@compareparameter+' not in (select '+@compareparameter+' from '+@table1+')' 
EXEC(@sql)

Answer 1

I think you want all rows from Table1 and Table2, such that each IDCodeField values only appears in one of the tables or the other. You wish to exclude rows where the same value appears in both tables.

Ignoring, for the moment, the question of what to do if the same value appears in the same table, the simplest query would be:

SELECT * from Table1 T1 full outer join Table2
ON T1.IDCodeField = T2.IDCodeField
WHERE T1.IDCodeField is null or T2.IDCodeField is null

This will give you the results, but possibly not in the format you’re seeking – the result rows will be as wide as both tables combined, and the columns from the non-matching table will be NULL.

Or, we could do it in the UNION style from your question.

SELECT * from Table1 where IDCodeField not in (select IDCodeField from Table2)
UNION ALL
SELECT * from Table2 where IDCodeField not in (select IDCOdeField from Table1)

Both of the above queries will return rows if the same IDCodeField value is duplicated only within a single table. If you wish to exclude this possibility, you might try finding the unique values first:

;With UniqueIDs as (
    SELECT IDCodeField
    FROM (
        SELECT IDCodeField from Table1
        union all
        select IDCodeField from Table2) t
    GROUP BY IDCodeField
    HAVING COUNT(*) = 1
)
SELECT * from (
    SELECT * from Table1
    union all
    select * from Table2
) t
  INNER JOIN
UniqueIDs u
  ON
    t.IDCodeField = u.IDCodeField

---

(Of course, all the uses of SELECT * above should be replaced with appropriate column lists)