Question

I have 3 tables. They have the same columns. I need to merge them into one table, such that I only have unique rows, the amount columns needs to be computed across the 3 tables.

e.g.

Table 1

Name1, 2, 100.00

Name5, 3, 25.00

---

Table 2

Name1, 2, 50.00

---

Table 3

Name1, 2, 60.00

---

Desired Result:

Name1, 2, 90.00 i.e. calculated as (100-60+50)

Name5, 3, 25.00

Any ideas? I’ve tried union but that doesn’t calculate for me or show unique rows….

Answer 1

Pretty clear question. Use UNION ALL to combine the tables into one queryable thing, then use GROUP BY to combine rows that share a value.

SELECT Col1, SUM(Col2) as Col2
FROM
(
SELECT Col1, Col2
FROM Table1
UNION ALL
SELECT Col1, Col2
FROM Table2
UNION ALL
SELECT Col1, Col2
FROM Table3
) as sub
GROUP BY Col1