MYSQL Using Union to combine two queries - mysql

Question

My first query looks as below
SELECT a.name, b.desc, T3.desc1 as Output
FROM table1 a INNER JOIN
table2 b
ON a.id = b.id
INNER JOIN (
SELECT b2.id, b2.status, MAX(b2.created_time) as max_time
FROM oac.qualys_scan b2
GROUP BY b2.id , b2.qualys_type
) t on t.id = a.id
AND t.status=b.status
AND t.max_time = b.created_time
INNER JOIN table3 T3 on b.tid = T3.tid
WHERE b.status = 'FAIL'
AND b.type = 'Type1'
My second query looks as below
SELECT a.name, b.desc, T4.desc2 as Output
FROM table1 a INNER JOIN
table2 b
ON a.id = b.id
INNER JOIN (
SELECT b2.id, b2.status, MAX(b2.created_time) as max_time
FROM oac.qualys_scan b2
GROUP BY b2.id , b2.qualys_type
) t on t.id = a.id
AND t.status=b.status
AND t.max_time = b.created_time
INNER JOIN table4 T4 on b.tid = T4.tid
WHERE b.status = 'FAIL'
AND b.type = 'Type2'
In my final result I want Output column which will have values either from T3.desc1 or T4.desc2
How can I use UNION to combine both queries into a single query?

Answer 1

just put UNION ALL between the queries. Youll have to alias the columns

Answer 2

Do this:
Query1 UNION Query2; -- for union without duplicates (the set union as in maths)
OR
Query1 UNION ALL Query2; -- for union with duplicates
So it should be:
SELECT a.name, b.desc, T3.desc1 as Output
FROM table1 a INNER JOIN
table2 b
ON a.id = b.id
INNER JOIN (
SELECT b2.id, b2.status, MAX(b2.created_time) as max_time
FROM oac.qualys_scan b2
GROUP BY b2.id , b2.qualys_type
) t on t.id = a.id
AND t.status=b.status
AND t.max_time = b.created_time
INNER JOIN table3 T3 on b.tid = T3.tid
WHERE b.status = 'FAIL'
AND b.type = 'Type1'
UNION
SELECT a.name, b.desc, T4.desc2 as Output
FROM table1 a INNER JOIN
table2 b
ON a.id = b.id
INNER JOIN (
SELECT b2.id, b2.status, MAX(b2.created_time) as max_time
FROM oac.qualys_scan b2
GROUP BY b2.id , b2.qualys_type
) t on t.id = a.id
AND t.status=b.status
AND t.max_time = b.created_time
INNER JOIN table4 T4 on b.tid = T4.tid
WHERE b.status = 'FAIL'
AND b.type = 'Type2';