Single SELECT combining multiple JOINs - select

Question

I'm trying to figure out how to write a SQL query that returns the result of two other SELECT statements, each with their own JOIN. Here's the scenario:
Table1 might have NULL values in the T1Number and/or T1State columns. Table2 might have rows with a matching number or state. I want all rows from Table1, but want to fill in any NULL T1Number with T2Number when the states match, and fill in any NULL T1State with T2State when the numbers match. I don't want rows from Table2 that don't have a matching state or number:
Table1: Table2:
Name T1Number T1State T2Number T2State
---- -------- ------- -------- -----
Joe 1 NULL 1 MA
Bob NULL CA 2 CA
Dan NULL NULL 3 FL
Sam 4 NY 4 NY
Ray 5 TX 8 PA
So I have one SELECT statement to get the Number:
SELECT
Table1.Name,
Table1.T1Number,
Table1.T1State,
Table2.T2Number,
Table2.T2State
FROM Table1
INNER JOIN Table2 ON Table2.T2State = Table1.T1State
WHERE (Table1.T1Number IS NULL OR Table1.T1State IS NULL)
Result:
Name T1Number T1State T2Number T2State
---- -------- ------- -------- -------
Bob NULL CA 2 CA
And another SELECT statement to get the State:
SELECT
Table1.Name,
Table1.T1Number,
Table1.T1State
Table2.T2Number
Table2.T2State
FROM Table1
INNER JOIN Table2 ON Table2.T2Number = Table1.T1Number
WHERE (Table1.T1Number IS NULL OR Table1.T1State IS NULL)
Result:
Name T1Number T1State T2Number T2State
---- -------- ------- -------- -------
Joe 1 NULL 1 MA
How do I write a combined SELECT statement that gives me the following desired result?
Name Number State
---- ------ -----
Joe 1 MA
Bob 2 CA
Dan NULL NULL
Sam 4 NY
Ray 5 TX
I assume I need a containing SELECT statement that does a LEFT JOIN between Table1 and the union of the above queries, but I know this is way easier than I'm making it. Many thanks in advance.

Answer 1

You could use a single select statement without the where clause and a case statement in your join operation. Something like:
SELECT t1.Name
, CASE WHEN t1.Number is null then t2.Number else t1.Number END as Number
, CASE WHEN t1.State is null then t2.State else t1.State end as State
FROM Table1 t1
LEFT JOIN Table2 t2
ON CASE WHEN t1.Number is null THEN t1.State
ELSE CONVERT(varchar(1), t1.Number) END
= CASE WHEN t1.Number is null THEN tab2.State
ELSE CONVERT(varchar(1), t2.Number) END