Question

I’m writing a Transact-SQL query which involves several UNIONS where, where the datatype of the second column is an int. The datatype of the first column is a varchar.

Here’s an example of the issue I’m having. In the SQL below, the query won’t run because it won’t let me leave the second column blank for that last SELECT statement. I put a blank varchar there (‘ ‘) but it requires an int, so am I forced to put in a dummy value like 0?

SELECT product, price
  FROM tableA    
UNION ALL    
SELECT '', SUM(price)
  FROM tableB    
UNION ALL    
SELECT '', ''
  FROM tableC

Answer 1

Why not select null and cast it to a number when really necessary?

SELECT product, price
FROM tableA

UNION ALL

SELECT '', SUM(price)
FROM tableB

UNION ALL

SELECT 'space', NULL
FROM tableC