Need help combining SQL queries

Question

SELECT 
    tableA.col1,
    tableA.col2,
    LEFT(tableB.col3, 4) as person

FROM tableA

LEFT JOIN tableB ON

    tableB.col1 = tableA.col1 AND
    tableB.col2 = tableA.col2

WHERE tableA.col3 = '000000'

AND tableA.col4 <> ''

AND person = 'Zeus'

ORDER BY tableA.col1, tableA.col4 ASC;

---

col1          col4        person
001           abc         Zeus
002           abc         Zeus
003           xyz         Zeus
004           xyz         Zeus

+

SELECT
    tableC.col1,
    SUM(tableC.col2) as cost

FROM tableC

WHERE tableC.col3 = 'L'

GROUP BY tableC.col1, tableC.col3;

---

col1          cost
001           23462
002           25215
003           92381
004           29171

=

col1          col4          person          cost
001           abc           Zeus            23462
002           abc           Zeus            25215
003           xyz           Zeus            92381
004           xyz           Zeus            29171

How do I do this? I tried putting the second query as a nested select in the top one, but I couldn't get it to work. Both result sets share the same col1 values, which are unique, so I guess they need to be joined on that? And ultimately the person is where the query will differ every time I run it.

Answer 1

You can try with an inner join on col1

SELECT tableA.col1, tableA.col2, LEFT(tableB.col3, 4) as person, tableC.col1, SUM(tableC.col2) as cost
FROM tableA
LEFT JOIN tableB ON ( tableB.col1 = tableA.col1 AND tableB.col2 = tableA.col2)
INNER JOIN tableC ON ( tableA.col1 = tableC.col1)
WHERE tableA.col3 = '000000'
AND tableA.col4 <> ''
AND person = 'Zeus'
GROUP BY tableA.col4, person, tableC.col1, tableC.col3;
ORDER BY tableA.col1, tableA.col4 ASC;