RE: next baby step in SQL: start using join

["DeLong, Eric" <EDeLong@xxxxxxxxxxxxxxx>]

Dan,

No, the retrieved query definitions do not produce optimal joins.  What
you're seeing is called a simple join, and it is the most basic and limited
of join syntax.  What you want is the formal join syntax...

Select .......
>From  lib/file1 <join type> join  lib/file2  on (file1.filedname =
file2.fieldname)

<join type> is commonly Inner, Left Outer, or Exception.

Eric DeLong
Sally Beauty Company
MIS-Project Manager (BSG)
940-898-7863 or ext. 1863



-----Original Message-----
From: Dan [mailto:dbcemid@xxxxxxxxx]
Sent: Thursday, March 27, 2003 3:10 PM
To: midrange-l@xxxxxxxxxxxx
Subject: next baby step in SQL: start using join


<This is the completed version of the original email.  Sorry, fat thumbs
today...>

I'm somewhat of an experienced simple user of SQL, i.e., never done any
joins.

I am now have what appears to be a perfect opportunity to use SQL join to
greatly simplify my
coding.  Knowing that one can use Retrieve Query Mgmt Query (RTVQMQRY) to
take a *QRYDFN and
generate the SQL via ALWQRYDFN(*YES), I use WRKQRY to set up the query, get
it working the way I
want it to, save the *QRYDFN, and use RTVQMQRY to generate the SQL.

So, I am surprised to see that the generated SQL doesn't have any Join
clauses (?) but, instead,
does the join via WHERE, i.e.:
 FROM      PQPROD/PESTCCP T01, 
           PQPROD/PTBLCCP T02, 
           PQPROD/PJOBHDR T03  
 WHERE     T03.CMPNUM = T02.CMPNUM 
   AND     T01.CCPTYP = T02.TBLID  
   AND     T01.CCPNUM = T02.CCPNUM 
   AND     T01.JOBNUM = T03.JOBNUM 
   AND(    T01.JOBNUM = 'TACM0170' 
   AND     T02.CSTTYP = 'C')       

The join in WRKQRY looks like this:
 Field             Test     Field        
 T03.CMPNUM        EQ       T02.CMPNUM   
 T01.CCPTYP        EQ       T02.TBLID    
 T01.CCPNUM        EQ       T02.CCPNUM   
 T01.JOBNUM        EQ       T03.JOBNUM   

So, what gives?  Is the RTVQMQRY generated SQL the best way to join?

TIA, Dan

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