From: | Paul Linehan <linehanp(at)tcd(dot)ie> |
---|---|
To: | |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | SQL problem (forgot to change header with earlier post!). |
Date: | 2018-05-29 11:14:39 |
Message-ID: | CAF4RT5S7AJ-Vt9KKL2vuJyu7M7yRbDFjbUWPsFFGTkW74kigkw@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
Hi all,
I have a problem that I just can't seem to solve:
I want to divide the count of one table by the count of another -
seems simple enough!
I created simple VIEWs with counts of the tables, but I just can't
grasp the logic!
DDL and DML (simplified) at the bottom of post.
I tried various combinations of things like basic SELECTs.
SELECT avg FROM ((SELECT cnt1 FROM v1)/(SELECT cnt2 FROM v2));
and I also tried to use CTEs as follows:
WITH num AS
(
SELECT cnt1 FROM v1
),
div AS
(
SELECT cnt2 FROM v2
)
SELECT (num.cnt1/div.cnt2);
Should you require any further information or if this should be on
another list, please don't hesitate to contact me and/or let me know.
I would appreciate a short explanation of where I'm going wrong also.
TIA and rgs,
Pól...
================== DDL and DML
CREATE TABLE t1 (x INT);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (4);
CREATE VIEW v1 AS (SELECT COUNT(*) AS cnt1 FROM t1);
CREATE TABLE t2 (y INT);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
INSERT INTO t2 VALUES (5);
From | Date | Subject | |
---|---|---|---|
Next Message | Andreas Kretschmer | 2018-05-29 11:37:14 | Re: binaries for 11 beta compiled with --with-llvm? |
Previous Message | Paul Linehan | 2018-05-29 11:12:33 | Re: binaries for 11 beta compiled with --with-llvm? |