I am trying to get this result in sql developer(emp table):
TOTAL 1980 1981 1982 1983
-------- --------- --------- --------- ---------
14 1 10 2 1
but I am getting :
TOTAL 1980 1981 1982 1983
-------- --------- --------- --------- ---------
13 1 10 2 1
Counting on the entire table gives me 14:
SELECT COUNT(*) FROM EMP;
Why does the count in this case return 13 not 14 ?
SELECT COUNT(*) TOTAL,
SUM(DECODE(EXTRACT(YEAR FROM HIREDATE),1980,COUNT(*))) "1980",
SUM(DECODE(EXTRACT(YEAR FROM HIREDATE),1981,COUNT(*))) "1981",
SUM(DECODE(EXTRACT(YEAR FROM HIREDATE),1982,COUNT(*))) "1982",
SUM(DECODE(EXTRACT(YEAR FROM HIREDATE),1983,COUNT(*))) "1983"
FROM EMP GROUP BY HIREDATE;
I think you want conditional aggregation:
SELECT COUNT(*) TOTAL,
SUM(CASE WHEN EXTRACT(YEAR FROM HIREDATE) = 1980 THEN 1 ELSE 0 END) as "1980",
SUM(CASE WHEN EXTRACT(YEAR FROM HIREDATE) = 1981 THEN 1 ELSE 0 END) as "198`",
SUM(CASE WHEN EXTRACT(YEAR FROM HIREDATE) = 1982 THEN 1 ELSE 0 END) as "1982",
SUM(CASE WHEN EXTRACT(YEAR FROM HIREDATE) = 1983 THEN 1 ELSE 0 END) as "1983"
FROM EMP;
Notes:
GROUP BY HIREDATE
. You only seem to want one row of output. DECODE()
is Oracle-specific. The ANSI standard for conditional expressions is CASE
. COUNT(*)
inside SUM()
). This is the cause of your problem. This version should fix the issue.
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