How about this?
CREATE TABLE t1(d INT,s INT, c INT);
CREATE UNIQUE INDEX idx01_t1
ON t1 USING btree (d, s, c);
INSERT INTO t1 (d, s, c)
VALUES (1,1,1),(2,2,2),(3,3,3),(4,4,4),(5,5,5);
CREATE TABLE t2(d INT,s INT, c INT, x boolean);
INSERT INTO t2(d, s, c, x)
VALUES (1,1,1,TRUE),(1,1,1,FALSE),(2,2,2,FALSE),(4,4,4,FALSE),(4,4,4,FALSE),(5,5,5,TRUE),(5,5,5,TRUE);
SELECT t1.d, t1.s, t1.c, CASE WHEN t2.x IS NULL THEN 0 ELSE COUNT(*) END
FROM t1
LEFT OUTER JOIN t2 ON t1.d = t2.d AND t1.s = t2.s AND t1.c = t2.c AND t2.x = TRUE
GROUP BY t1.d, t1.s, t1.c,t2.x;
--DROP TABLE t1;
--DROP TABLE t2;
On Fri, Feb 20, 2009 at 12:04 PM, Tarlika Elisabeth Schmitz
<postgresql@numerixtechnology.de> wrote:
> I have 2 tables T1 and T2
>
> T1 has the columns: D, S, C. The combination of D,S,C is unique.
> T2 has the columns: D, S, C, and boolean X. The combination of D,S,C is
> not unique.
>
> I need to produce the following result for every occurrence of T1:
> D,S,C, COUNT
>
> COUNT is the number of matching D,S,C combinations in T2 where X = true.
> There might be no matching pair in T2 or there might be match but X
> is false.
>
> How can I express this?
>
>
>
> --
>
>
> Best Regards,
>
> Tarlika Elisabeth Schmitz
>
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