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
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
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
使用SELECT COUNT(*) FROM t WHERE a = current_a AND c = 'const' ) as d
。
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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