
Question:
I would like to embed a SELECT inside a COUNT, but I can't find any examples.
#pseudosql SELECT a AS current_a, COUNT(*) AS b, COUNT( SELECT FROM t WHERE a = current_a AND c = 'const' ) as d, from t group by a order by b desc
Solution:1
You don't really need a sub-select:
SELECT a, COUNT(*) AS b, SUM( CASE WHEN c = 'const' THEN 1 ELSE 0 END ) as d, from t group by a order by b desc
Solution:2
You can move the count() inside your sub-select:
SELECT a AS current_a, COUNT(*) AS b, ( SELECT COUNT(*) FROM t WHERE a = current_a AND c = 'const' ) as d, from t group by a order by b desc
Solution:3
Use SELECT COUNT(*) FROM t WHERE a = current_a AND c = 'const' ) as d
.
Solution:4
SELECT a AS current_a, COUNT(*) AS b, (SELECT COUNT(*) FROM t WHERE a = current_a AND c = 'const' ) as d from t group by a order by b desc
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