Join SQL Server Showing Duplicate Row - sql

Question

I want to ask something about joining query. I have a query like this:
SELECT b.compilecodingid,
a.subjobfamily,
b.position,
b.nocoding,
( CASE
WHEN (SELECT Count(0)
FROM trlspbia
WHERE learningsystemid = a.learningsystemid
AND compilecodingid = b.compilecodingid
AND moduleid = '2018081616230361362303614'
AND learningroadmap = 'Basic') > 0 THEN 1
ELSE 0
END ) AS CountPickPBIA
FROM trlsplanning a,
trcompilecodingheader b
WHERE a.learningsystemid = b.learningsystemid
AND a.position = b.position
AND a.learningsystemid = '2018081513283162000000001'
order by CountPickPBIA desc
I know it's because Column Position on Table TrLsPlanning has more than 1 data,
Anyone can help me to find the solution?
Thank you.

Answer 1

The simplest solution is probably select distinct:
SELECT cch.compilecodingid, p.subjobfamily, cch.position, cch.nocoding,
(CASE WHEN EXISTS (SELECT 1
FROM trlspbia s
WHERE s.learningsystemid = p.learningsystemid AND
s.compilecodingid = ccb.compilecodingid AND
s.moduleid = '2018081616230361362303614' AND
s.learningroadmap = 'Basic'
)
THEN 1
ELSE 0
END) AS CountPickPBIA
FROM trlsplanning p JOIN
trcompilecodingheader cch
ON p.learningsystemid = cch.learningsystemid AND
p.position = cch.position
WHERE p.learningsystemid = '2018081513283162000000001'
ORDER BY CountPickPBIA DESC;
SELECT DISTINCT incurs its own overhead. But without more information about the structure and contents of the table, this is the simplest solution.
Note other changes in the query:
Table aliases are abbreviations for table names, rather than being arbitrary letters.
The JOIN syntax is fixed, to use modern, proper, and standard JOIN/ON.
All columns are qualified with the table alias, particularly those in the correlated subqueries.
The subquery uses EXISTS rather than COUNT(*). This is both more efficient and it probably better expresses the logic you want.