MySQL子查询WHERE IN，但也可以从IN子查询中获取其他列

Question

This is slipping my mind at the moment, so let's say I have this code:

SELECT * FROM Table1
    WHERE (FoundCity, FoundState) IN
    ( SELECT city, state, distance
      FROM Table2
    ) ;

How do I also get it to pull the distance column above into the 'main' query?

Answer 1

SELECT * FROM Table1 as T1
LEFT JOIN Table2 as T2 on T1.FoundCity = T2.FoundCity AND T1.FoundState = T2.FoundState 

Better idea would be to use Left join. And in * you can include column names you desire using T1 as prefix for columns from table 1 and T2 for table 2. (ex: T2.state)

Answer 2

Change the subquery to a join. You can then select any of the columns from either table.

SELECT *,  t2.distance
FROM Table1 t1
INNER JOIN Table2 t2
ON t1.FoundCity = t2.city AND t1.FoundState = t2.state

Edit

If you want to keep the Tuple join syntax, you can also do:

SELECT t1.*, t2.distance
    FROM t1 INNER JOIN t2
    ON (t1.FoundCity, t1.FoundState) = (t2.city, t2.state);

SqlFiddle