[SQL] No Not join

[Ruslan Zasukhin]

on 9/15/03 5:35, David Hood at david.hood at stonebow.otago.ac.nz wrote:

Hi David,

> On the current VAPP the SQL statement
> 
> "SELECT table1.*, table2.* FROM table1, table2 WHERE
> ((Table1.ID=Table2.ID2) and (Table1.Code=Table2.Code2)) and
> (Table1.Year=1900) and (Table2.Year2=1910)"
> 
> Runs fine giving expected results
> 
> 
> "SELECT table1.*, table2.* FROM table1, table2 WHERE
> ((table1.ID=Table2.ID2) and (Table1.Code!=Table2.Code2)) and
> (Table1.Year=1900) and (Table2.Year2=1910)"
> 
> Runs and ignores the (Table1.Code!=Table2.Code2) criteria when
> producing results

Valentina 1.x can do joins based on operator = only.


> "SELECT table1.*, table2.* FROM table1, table2 WHERE
> ((table1.ID=Table2.ID2) and (Table1.Code<>Table2.Code2)) and
> (Table1.Year=1900) and (Table2.Year2=1910)"
> 
> Fails with an aggregate function warning message
> 
> Since both the second and third query work fine in MYSQL I suspect it's
> a parser issue.

More correctly, this require other much slower algorithm of join that
operator =. 

As for me, I believe that such design -- with 2 fields on join is OLD RDBMS
way. It is always better to have just one link fields.

Can you explain me (just for interest) the logic of above your 2 linked
tables and logic of above queries with <> ?

-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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