SQL Query - Using Order By in UNION

How can one programmatically sort a union query when pulling data from two tables? For example,

SELECT table1.field1 FROM table1 ORDER BY table1.field1
UNION
SELECT table2.field1 FROM table2 ORDER BY table2.field1

Throws an exception

Note: this is being attempted on MS Access Jet database engine

Solution 1:

Sometimes you need to have the ORDER BY in each of the sections that need to be combined with UNION.

In this case

SELECT * FROM 
(
  SELECT table1.field1 FROM table1 ORDER BY table1.field1
) DUMMY_ALIAS1

UNION ALL

SELECT * FROM
( 
  SELECT table2.field1 FROM table2 ORDER BY table2.field1
) DUMMY_ALIAS2

Solution 2:

SELECT field1 FROM table1
UNION
SELECT field1 FROM table2
ORDER BY field1

Solution 3:

I think this does a good job of explaining.

The following is a UNION query that uses an ORDER BY clause:

select supplier_id, supplier_name
from suppliers
where supplier_id > 2000
UNION
select company_id, company_name
from companies
where company_id > 1000
ORDER BY 2;

Since the column names are different between the two "select" statements, it is more advantageous to reference the columns in the ORDER BY clause by their position in the result set.

In this example, we've sorted the results by supplier_name / company_name in ascending order, as denoted by the "ORDER BY 2".

The supplier_name / company_name fields are in position #2 in the result set.

Taken from here: http://www.techonthenet.com/sql/union.php