Question

I am unsure as to how to resolve an ambiguous column reference when using an alias.

Imagine two tables, a and b that both have a name column. If I join these two tables and alias the result, I do not know how to reference the name column for both tables. I’ve tried out a few variants, but none of them work:

Attempt 1

SELECT a.name, b.name
FROM (a INNER JOIN b ON a.id = b.id) AS x

This doesn’t work as a and b are out of scope.

Attempt 2

SELECT x.a.name, x.b.name
FROM (a INNER JOIN b ON a.id = b.id) AS x

SQL syntax doesn’t work like that.

Attempt 3

SELECT x.name, x.name
FROM (a INNER JOIN b ON a.id = b.id) AS x

That’s just plain ambiguous!

I’m all out of ideas – any help would be much appreciated.

Answer 1

don’t enclose it with parenthesis since (a INNER JOIN b ON a.id = b.id) is not a complete query.

SELECT  a.name AS A_Name, 
        b.name AS B_Name
FROM    a INNER JOIN b 
           ON a.id = b.id

or (assuming) if you have longer tables names and you want to make it short,

SELECT  a.name AS A_Name, 
        b.name AS B_Name
FROM    longTableNameA a 
        INNER JOIN longTableNameB b 
           ON a.id = b.id