Question

I’m running into a problem that I cannot figure out for some reason. I am trying to write a query that joins two tables, in which a match may not be found in a table. Such as:

SELECT 
    Table1.IDField, Table2.IDField
FROM 
    Table1
LEFT OUTER JOIN 
    Table2 ON Table1.PersonID = Table2.PersonID
WHERE 
    (Table1.IDField = '12345')
    AND (Table2.Category = 'Foo')

If there is no match in Table2, it’s not returning anything. However, I need it to just return a NULL for that column if there is no match and still return the value from Table1.

I have changed up the JOIN with everything that I can think of, but to no avail.

Table2.Category can contain multiple other values, so doing a OR IS NULL type of deal won’t work.

So, if there is no match for Table2.Category = 'Foo', I am still needing it to return:

Table1 | Table2
----------------
 12345 |  NULL

Any suggestions?

Answer 1

Move the condition for table2 out of your WHERE clause and into your JOIN.

SELECT 
    Table1.IDField, Table2.IDField
FROM 
    Table1
LEFT OUTER JOIN Table2 
    ON Table1.PersonID = Table2.PersonID
    AND Table2.Category = 'Foo'
WHERE 
    Table1.IDField = '12345'