August 21, 2012 at 4:09 am
create table A
(a int, b int)
create table D
(a int)
insert into A values (1,1)
insert into A values (2,1)
insert into A values (1,2)
insert into A values (4,2)
-- this table has other values.
insert into D values (1)
insert into D values (2)
insert into D values (3)
insert into D values (4)
-- I want to join A & D based on a values where A.b = 1
SELECT * FROM D
LEFT OUTER JOIN a
ON A.a = D.a
WHERE A.b = 1
-- but have the D values 3 & 4 show up with NULL where the A values should be :
-- like this:
111
221
3 null null
4 null null
-- In reality, it's more complex based on a big IN clause that I'm trying to avoid using twice.
SELECT * FROM D
LEFT OUTER JOIN a
ON A.a = D.a
WHERE A.b = 1
AND D.a IN
(1,2,3,4)
-- Appreciate any help!
August 21, 2012 at 4:19 am
SELECT a2.a, D.a
FROM D
LEFT JOIN
(
SELECT * FROM A
WHERE A.b = 1
) AS a2
ON a2.a = D.a
WHERE D.a IN (1,2,3)
oh dear. i think the act of clarifying in a post sorted my brain out & the above code does what I need. sorry to have bothered!!
one of those days.
🙂
August 21, 2012 at 4:23 am
Like this?
SELECT * FROM D
LEFT JOIN (SELECT *
FROM
A
WHERE
A.b = 1
) AS A
ON D.a = A.B
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A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratcliffe
August 21, 2012 at 4:24 am
Didn't see you had already sorted it!
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A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratcliffe
August 21, 2012 at 4:27 am
You need to put the condition in the join clause:
SELECT D.a, A.a, A.b
FROM D
LEFT OUTER JOIN A
ON A.a = D.a And A.b=1
WHERE A.b = 1 or A.b is null
August 21, 2012 at 4:30 am
In fact you don't need the WHERE clause:
SELECT D.a, A.a, A.b
FROM D
LEFT OUTER JOIN A
ON A.a = D.a And A.b=1
...but you've fixed it. Anyway - there are a few ideas there...
August 21, 2012 at 4:37 am
Thank you both!! Appreciate you taking the time.
🙂
August 21, 2012 at 4:41 am
SELECT *
FROM D
LEFT OUTER JOIN a
ON A.a = D.a
WHERE
A.b = 1 -- << this turns the LEFT OUTER JOIN into an INNER JOIN
AND D.a IN (1,2,3,4)
-- use this instead:
SELECT *
FROM D
LEFT OUTER JOIN a
ON A.a = D.a AND A.b = 1
WHERE D.a IN (1,2,3,4)
Ah, Laurie beat me to it.
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden
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