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Message
From
12/09/2001 11:53:47
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivia
 
 
To
12/09/2001 11:42:32
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Title:
Miscellaneous
Thread ID:
00555540
Message ID:
00555555
Views:
13
Warning - If you follow Nadya's suggestion, if one table has 100 records, and the other 1000, you will get 100,000 records in the result set. This is called a "Cartesian Product". It is usually very wrong - but there are cases where I found it actually useful to use a Cartesian Product.

To avoid confusion, I suggest documenting every case where you use a Cartesian Product on purpose, like this:
* Cartesian Product is on purpose.
select Table1.Field1, Table2.Field2;
  from Table1, Table2;
  into cursor TempResult
Hilmar.

>Hi,
>
>I rarely, if ever have done full outer joins before. (basically all data in table a joined with all data in table b) I am not sure of the syntax,
>
>
>select curRules.question, curRules.ansdescrip, curRules2.question2, ;
>        curRules2.ansdescrip ;
>	FROM curRules FULL OUTER JOIN curRules2 ;
>	INTO CURSOR curRules3
>
>
>The thing that confuses me is what I put in the 'ON' part. There are no fields that have to be equal.
>
>Thanks,
>Chris
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
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