I should have pointed out that the Jobs table is related to the Members
table rather than the Family table. I attempted to join the member and
job tables first and then join the member table to the family table but
couldn't figure out how to do so. The sample code I presented was
intended to show how the tables are linked. I realize now that it does
use a join. I didn't show my actual code assuming it might be simpler
for a Pro to simply give me a solution that works rather than trying to
figure out my approach.
Thanks - Joe
On Friday, February 13, 2009 9:28 AM, Stephen Russell wrote:
>
>Date: Fri, 13 Feb 2009 08:28:19 -0600
>From: Stephen Russell
>To: profoxt...@leafe.com
>cc:
>Subject: Re: SQL help for an additional level
>
>On Fri, Feb 13, 2009 at 7:45 AM, Joe Yoder <j...@wheypower.com> wrote:
>> I asked this question earlier without the Jobs component. I now understand
>> how to handle that one with a join but haven't figured out how to join a
>> join. As before this code gives me a single record but I need one for the
>> case where there is no Typ2.
>> TIA - Joe Yoder
>>
>> CREATE CURSOR Family (Id I)
>> CREATE CURSOR Members (Parent I, Type C(1), Jcode C(1))
>> CREATE CURSOR Jobs (Code C(1), Desc C(1))
>>
>> INSERT INTO Family (Id) VALUES (1)
>> INSERT INTO Family (Id) VALUES (2)
>> INSERT INTO Members (Parent, Type, Jcode) VALUES (1, 'a', '1')
>> INSERT INTO Members (Parent, Type, Jcode) VALUES (1, 'b', '2')
>> INSERT INTO Members (Parent, Type, Jcode) VALUES (2, 'a', '3')
>> INSERT INTO Jobs (Code, Desc) VALUES ('1', 'A')
>> INSERT INTO Jobs (Code, Desc) VALUES ('2', 'B')
>> INSERT INTO Jobs (Code, Desc) VALUES ('3', 'C')
>>
>> SELECT Family.Id, M1.Type as Typ1, M2.Type as Typ2, J1.Desc as Job1,
>> J2.Desc as Job2;
>> FROM Family, Members as M1, Members as M2, Jobs as J1, Jobs as J2;
>> WHERE Family.Id = M1.Parent AND M1.Type = 'a';
>> AND Family.Id = M2.Parent AND M2.Type = 'b';
>> AND J1.code = M1.Jcode;
>> AND J2.code = M2.Jcode
>
>--------------------------------
>
>A good habit to get into is to USE the "join" and keep it's "on"
>conditions together. You don't show any joins. Not a good way to
>write SQL syntax that could be promoted to other backends is my point.
>
>
>FROM Family,
>join Members as MA
>on Family.Id = MA.Parent AND MA.Type = 'a'
>
>join Members as MB
>on Family.Id = MB.Parent AND MB.Type = 'b';
>
>join Jobs as JA
>on JA.code = MA.Jcode;
>
>join Jobs as JB
>on JB.code = MB.Jcode;
>
>You will need to create an index on Members that is compound of Parent
>and Type and Jcode.
>
>It has been a long time since I tweaked VFP indexes but you may not
>get the performance out of this if they are different data types. Int
>/ Char. I know that in mySQL or others this would not be an issue.
>
>Second point I changed in your code was to represent in the LETTER of
>demand in your join condition in its Name M1 is really MA same with JB
> not J2
>
>Trust me years later when you have to come back to this it will all
>look much clearer.
>
>In VFP9 can you use joins to create temp data
>
>select <field list>
>from Members m.ID
>left join
>(
>select MA.ID, MA.Description, JA.Description
>from Members MA
>join Jobs JA
>on JA.code = MA.Jcode
>) as MemJobsA
>on M.id = MemJobsA.ID
>
>< put in stuff for the "B" here >
>
>where < my criteria exists >
>
>I thought that I heard long ago that VFP9 sql syntax got more robust
>in this area.
>
>HTH
>
>--
>Stephen Russell
>Sr. Production Systems Programmer
>First Horizon Bank
>Memphis TN
>
>901.246-0159
>
[excessive quoting removed by server]
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