SQL Clone
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 


Annoying join problem & frozen brain.


Annoying join problem & frozen brain.

Author
Message
snomadj
snomadj
Old Hand
Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)

Group: General Forum Members
Points: 300 Visits: 649
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:
1 1 1
2 2 1
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!
snomadj
snomadj
Old Hand
Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)

Group: General Forum Members
Points: 300 Visits: 649
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.

Smile
Andy Hyslop
Andy Hyslop
SSC Eights!
SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)

Group: General Forum Members
Points: 981 Visits: 3037
Like this?


SELECT * FROM D
LEFT JOIN ( SELECT *
FROM
A
WHERE
A.b = 1
) AS A
ON D.a = A.B



==========================================================================================================================
A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratcliffe
Andy Hyslop
Andy Hyslop
SSC Eights!
SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)SSC Eights! (981 reputation)

Group: General Forum Members
Points: 981 Visits: 3037
Didn't see you had already sorted it!

==========================================================================================================================
A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratcliffe
laurie-789651
laurie-789651
SSChasing Mays
SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)

Group: General Forum Members
Points: 618 Visits: 1272
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



laurie-789651
laurie-789651
SSChasing Mays
SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)SSChasing Mays (618 reputation)

Group: General Forum Members
Points: 618 Visits: 1272
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...
snomadj
snomadj
Old Hand
Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)Old Hand (300 reputation)

Group: General Forum Members
Points: 300 Visits: 649
Thank you both!! Appreciate you taking the time.

Smile
ChrisM@Work
ChrisM@Work
SSCoach
SSCoach (16K reputation)SSCoach (16K reputation)SSCoach (16K reputation)SSCoach (16K reputation)SSCoach (16K reputation)SSCoach (16K reputation)SSCoach (16K reputation)SSCoach (16K reputation)

Group: General Forum Members
Points: 16406 Visits: 19554
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.

“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw

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
Exploring Recursive CTEs by Example Dwain Camps
Go


Permissions

You can't post new topics.
You can't post topic replies.
You can't post new polls.
You can't post replies to polls.
You can't edit your own topics.
You can't delete your own topics.
You can't edit other topics.
You can't delete other topics.
You can't edit your own posts.
You can't edit other posts.
You can't delete your own posts.
You can't delete other posts.
You can't post events.
You can't edit your own events.
You can't edit other events.
You can't delete your own events.
You can't delete other events.
You can't send private messages.
You can't send emails.
You can read topics.
You can't vote in polls.
You can't upload attachments.
You can download attachments.
You can't post HTML code.
You can't edit HTML code.
You can't post IFCode.
You can't post JavaScript.
You can post emoticons.
You can't post or upload images.

Select a forum

































































































































































SQLServerCentral


Search