How to Left Inner Join two queries in Sybase? - sybase

Question

I have two queries that should be joined together. Here is my query 1:
SELECT
t1.rec_id,
t1.category,
t1.name,
t1.code,
CASE
WHEN t1.name= 'A' THEN SUM(t1.amount)
WHEN t1.name = 'D' THEN SUM(t1.amount)
WHEN t1.name = 'H' THEN SUM(t1.amount)
WHEN t1.name = 'J' THEN SUM(t1.amount)
END AS Amount
FROM Table1 t1
GROUP BY t1.name, t1.rec_id, t1.category, t1.code
Query 1 produce this set of results:
Rec ID Category Name Code Amount
1 1 A MIX 70927.00
1 3 D MIX 19922.00
1 2 H MIX 55104.00
1 4 J MIX 76938.00
Then I have query 2:
SELECT
CASE
WHEN t2.category_id = 1 THEN SUM(t2.sum)
WHEN t2.category_id = 2 THEN SUM(t2.sum)
WHEN t2.category_id = 3 THEN SUM(t2.sum)
WHEN t2.category_id = 4 THEN SUM(t2.sum)
END AS TotalSum
FROM Table2 t2
INNER JOIN Table1 t1
ON t1.amnt_id = t2.amnt_id
AND t2.unique_id = #unique_id
GROUP BY t2.category_id
The result set of query 2 is this:
TotalSum
186013.00
47875.00
12136.00
974602.00
All I need is this result set that combines query 1 and query 2:
Rec ID Category Name Code Amount TotalSum
1 1 A MIX 70927.00 186013.00
1 3 D MIX 19922.00 47875.00
1 2 H MIX 55104.00 12136.00
1 4 J MIX 76938.00 974602.00
As you can see there is connection between table 1 and table 2. That connection is amnt_id. However, I tried doing LEFT INNER JOIN on query 1 and then simply using same logic with case statement to get the total sum for table 2. Unfortunately Sybase version that I use does not support Left Inner Join. I'm wondering if there is other way to join these two queries? Thank you

Answer 1

I wondered if the CASE statement makes sense in the first query because it sums in every row. Are there other values for the name column except A, D, H, J? If not you can change the CASE statement to SUM(t1.amount) AS Amount. Also the GROUP BY in the first query seems dubious to me: you are grouping by the record id column - that means you are not grouping at all but instead return every row. If that is what you really want you can omit the SUM at all and just return the pure amount column.
As far as I understood your problem and your data structure: the values in Table2 are kind of category sums and the values in Table1 are subsets. You would like to see the category sum for every category in Table1 next to the single amounts?
You would typically use a CTE (common table expression, "WITH clause") but ASE doesn't support CTEs, so we have to work with joins. I recreated your tables in my SQL Anywhere database and put together this example. In a nutshell: both queries are subqueries in an outer query and are left joined on the category id:
SELECT *
FROM
(
SELECT
t1.rec_id,
t1.category,
t1.name,
t1.code,
CASE
WHEN t1.name= 'A' THEN SUM(t1.amount)
WHEN t1.name = 'D' THEN SUM(t1.amount)
WHEN t1.name = 'H' THEN SUM(t1.amount)
WHEN t1.name = 'J' THEN SUM(t1.amount)
END AS Amount
FROM Table1 t1
GROUP BY t1.rec_id, t1.name, t1.category, t1.code
) AS t1
LEFT JOIN
(
SELECT category_id, SUM(sum) FROM
table2
GROUP BY category_id
) AS totals(category_id, total_sum)
ON totals.category_id = t1.category;
This query gives me:
Rec ID Category Name Code Amount Category_id total_sum
2 3 D MIX 19922.00 3 47875.00
3 2 H MIX 55104.00 2 12136.00
1 1 A MIX 70927.00 1 186013.00
4 4 J MIX 76938.00 4 974602.00
You surely have to tweak it a bit including your t2.unique_id column (that I don't understand from your queries) but this is a practical way to work around ASE's missing CTE feature.
BTW: it's either an INNER JOIN (only the corresponding records from both tables) or a LEFT (OUTER) JOIN (all from the left, only the corresponding records from the right table) but a LEFT INNER JOIN makes no sense.