So -- what's the field that relates a booking to an allocation? Do they
share a project_ID or what? If they do, you might try this:
SELECT DISTINCT U.User_ID, U.User_Firstname, U.User_Lastname
FROM Users U
LEFT JOIN Allocations A
on A.User_ID = U.User_ID
LEFT JOIN Bookings B
ON B.User_ID = U.User_ID
WHERE A.Project_ID = '11'
OR B.Project_ID = '11'
ORDER BY User_Firstname;
<soapbox>
A pet peeve of mine is when people 'quote' NUMBERS. According to the
extremely well written manual, you only need to quote STRING values and
DATETIME values. Unless the columns Project_ID and Booking_ID are some
form of STRING column (CHAR, VARCHAR, TEXT, etc.) you don't need to quote
their values in queries. It forces the query engine to perform an
unnecessary internal type conversion. Here is what I think your query
should look like:
SELECT DISTINCT U.User_ID, U.User_Firstname, U.User_Lastname
FROM Users U
LEFT JOIN Allocations A
on A.User_ID = U.User_ID
LEFT JOIN Bookings B
ON B.User_ID = U.User_ID
WHERE A.Project_ID = 11
OR B.Project_ID = 11
ORDER BY User_Firstname;
</soapbox>
I used SELECT DISTINCT so that in the event that someone was both BOOKED
and ALLOCATED to the same project, you only got them listed once.
Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine
"shaun thornburgh" <[EMAIL PROTECTED]> wrote on 12/23/2004
08:37:37 AM:
> Hi,
>
> Thanks for your reply but that produces exactly the same result...
>
> Any ideas?
>
> >From: Sasha Pachev <[EMAIL PROTECTED]>
> >To: shaun thornburgh <[EMAIL PROTECTED]>
> >CC: mysql@lists.mysql.com
> >Subject: Re: Help with a join query please!
> >Date: Tue, 21 Dec 2004 14:57:43 -0700
> >
> >shaun thornburgh wrote:
> >>Hi,
> >>
> >>I have (among others) three tables in my database that i am struggling
> >>with a join query on. The database holds dates for Bookings. If Users
are
> >>Allocated to a particular Project they can be booked. However if a
user is
> >>booked but then unallocated I want to be able to display all peolple
> >>allocated to that project plus the person originally booked. Here are
my
> >>efforts so far:
> >>
> >>SELECT U.User_ID, U.User_Firstname, U.User_Lastname
> >>FROM Allocations A, Users U
> >>LEFT JOIN Bookings B
> >>ON B.User_ID = U.User_ID
> >>AND B.Booking_ID = '4512'
> >>WHERE U.User_ID = A.User_ID
> >>AND A.Project_ID = '11'
> >>ORDER BY User_Firstname;
> >
> >Shaun:
> >
> >If I understand the problem right, it sounds like you are missing AND
> >B.Bookings_ID is NULL in the where clause.
> >
> >
> >
> >--
> >Sasha Pachev
> >Create online surveys at http://www.surveyz.com/
> >
> >--
> >MySQL General Mailing List
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> >
>
>
>
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