SQL include entries with no data - sql

Question

Here is my sql statement in Oracle that I am working with:
SELECT FACILITY.fac_name
, SUM(FEE_LOG.fee_amount) AS TOTAL_FEES
FROM FACILITY
, BOOK_DETAIL
, TRANS_LOG
, FEE_LOG
, TRANS_TYPE
WHERE
FACILITY.fac_id = BOOK_DETAIL.fac_id
AND BOOK_DETAIL.bkdt_id = TRANS_LOG.bkdt_id
AND TRANS_LOG.trans_id = FEE_LOG.trans_id
AND TRANS_LOG.trans_type_id = TRANS_TYPE.trans_type_id
AND
(
TRANS_TYPE.trans_type_desc = 'LOST'
OR TRANS_TYPE.trans_type_desc = 'CHECKIN'
)
GROUP BY FACILITY.fac_name;
It outputs something similar to this:
FACILITY TOTAL_FEES
Facility 1 8.45
Facility 2 4.23
Facility 3 5.23
I have 2 other facilities but they do not have any fees associated with them. I want to show them as 0
So the output would be like:
FACILITY TOTAL_FEES
Facility 1 8.45
Facility 2 4.23
Facility 3 5.23
Facility 4 0
Facility 5 0
ER Diagram

Answer 1

Use LEFT JOIN instead of implicit INNER JOIN for the FEE_LOG table
SELECT FACILITY.fac_name
, SUM(FEE_LOG.fee_amount) AS TOTAL_FEES
FROM FACILITY
JOIN BOOK_DETAIL ON FACILITY.fac_id = BOOK_DETAIL.fac_id
JOIN TRANS_LOG ON BOOK_DETAIL.bkdt_id = TRANS_LOG.bkdt_id
LEFT JOIN FEE_LOG ON TRANS_LOG.trans_id = FEE_LOG.trans_id
JOIN TRANS_TYPE TRANS_LOG.trans_type_id = TRANS_TYPE.trans_type_id
WHERE TRANS_TYPE.trans_type_desc IN ('LOST', 'CHECKIN')
GROUP BY FACILITY.fac_name;

Answer 2

Use outer joins and the on clause:
SELECT FACILITY.fac_name, SUM(nvl(FEE_LOG.fee_amount,0)) AS TOTAL_FEES
FROM FACILITY
left join BOOK_DETAIL
on FACILITY.fac_id = BOOK_DETAIL.fac_id
left join TRANS_LOG
on BOOK_DETAIL.bkdt_id = TRANS_LOG.bkdt_id
left join FEE_LOG
on TRANS_LOG.trans_id = FEE_LOG.trans_id
left join TRANS_TYPE
on TRANS_LOG.trans_type_id = TRANS_TYPE.trans_type_id
and TRANS_TYPE.trans_type_desc in ('LOST', 'CHECKIN')
GROUP BY FACILITY.fac_name;
Note: If these facilities you are referring to, that do not have any fees, have rows on BOOK_DETAIL or TRANS_LOG you can replace the outer join with an inner join (for just those tables). Any table at which point there may or may not be a related record you have to use an outer join.

Answer 3

Try this:
SELECT f.fac_name
, coalesce(SUM(fl.fee_amount),0) AS TOTAL_FEES
FROM FACILITY AS f
INNER JOIN BOOK_DETAIL AS bd
ON bd.fac_id = f.fac_id
INNER JOIN TRANS_LOG AS tl
ON tl.bkdt_id = bd.bkdt_id
LEFT OUTER JOIN FEE_LOG AS fl
ON fl.trans_id = tl.trans_id
INNER JOIN TRANS_TYPE AS tt
ON tt.trans_type_id = tl.trans_type_id
WHERE tt.trans_type_desc in ('LOST' , 'CHECKIN')
GROUP BY f.fac_name;
NB: when you list tables after from with commas between them you're effectively using a cross join.
When you add a condition to your where statement matching a field from one table to a field from another, the join becomes an inner join.
To select all records from one table along with any matches which may or may not exist from another you need an outer join.
There are 3 types:
left outer join where you want all records from the first table listed and any matching records from the second.
right outer join for all records from the second with only matches from the first.
full outer join is all records from both tables, alongside one another where there's a match.
You should always specify the type of join rather than implying it through where clauses / commas, as this makes your intentions clearer and thus your code more readable.