missing expression in Select SQL - sql

Question

I'm new to SQL and sub queries, When I run the sub query by itself I get the correct data output. But when I run the full query I get the error message
SELECT * Error at line 3: ORA-00936: missing expression
Here's my code:
SELECT
MAX(
SELECT
SUM(
ALLOCATION.HourlyRate
*
ACTION.HrsWorked
)
FROM ALLOCATION
INNER JOIN ACTION
ON ((ACTION.ActId = ALLOCATION.ActId) AND (ACTION.EmpId = ALLOCATION.EmpId))
GROUP BY (ALLOCATION.ActId)
)
FROM ALLOCATION
GROUP BY (ALLOCATION.ActId)
SOLUTION:
SELECT MAX(sum_total_pay)
FROM
(
SELECT SUM(ALLOCATION.HourlyRate * ACTION.HrsWorked) AS sum_total_pay
FROM ALLOCATION
INNER JOIN ACTION
ON ((ACTION.ActId = ALLOCATION.ActId) AND (ACTION.EmpId = ALLOCATION.EmpId))
GROUP BY (ALLOCATION.ActId)
);

Answer 1

You needs two parentheses more :)
SELECT MAX ( ( SELECT SUM (ALLOCATION.HourlyRate * ACTION.HrsWorked)
FROM ALLOCATION INNER JOIN ACTION ON (ACTION.ActId = ALLOCATION.ActId) AND (ACTION.EmpId = ALLOCATION.EmpId)
GROUP BY (ALLOCATION.ActId)))
FROM ALLOCATION
GROUP BY ALLOCATION.ActId
The Select into MAX have to be in paranthesis.
The logic is not clear. This give you the total pay per activity:
SELECT ALLOCATION.ActId, SUM (ALLOCATION.HourlyRate * ACTION.HrsWorked) total_pay
FROM ALLOCATION b INNER JOIN ACTION ON ACTION.ActId = ALLOCATION.ActId AND ACTION.EmpId = ALLOCATION.EmpId
GROUP BY ALLOCATION.ActId
If you want to see, which activity has the biggest payment, then order by desc :
SELECT *
FROM ( SELECT ALLOCATION.ActId, SUM (ALLOCATION.HourlyRate * ACTION.HrsWorked) total_pay
FROM ALLOCATION b INNER JOIN ACTION ON ACTION.ActId = ALLOCATION.ActId AND ACTION.EmpId = ALLOCATION.EmpId
GROUP BY ALLOCATION.ActId)
ORDER BY total_pay DESC