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Re: Basic Database Question

From: <systems_ho/VGIL_at_vguard.satyam.net.in>
Date: Wed, 15 May 2002 21:08:22 -0800
Message-ID: <F001.00461E8E.20020515210822@fatcity.com>


Hello

Even if any one table in a select contains no data,use of outer join will retrieve rows for you.Please note that outer join operator (+) is not allowed in operand of OR or IN.

Regards
System.

|--------+----------------------->

| | "Gavin |
| | D'Mello" |
| | <gavin_d_at_tis.|
| | co.in> |
| | |
| | 05/15/02 |
| | 07:33 PM |
| | Please |
| | respond to |
| | ORACLE-L |
| | |
|--------+-----------------------> >--------------------------------------------------------| | | | To: Multiple recipients of list ORACLE-L | | <ORACLE-L_at_fatcity.com> | | cc: (bcc: systems ho/VGIL) | | Subject: Basic Database Question | >--------------------------------------------------------|

Hi I'm just about to ask a really trivial question which has never struck me before.

If i write a simple select like

select c.contentid from content c,
persusercontentassoc p,
teachercontentassoc t
where
t.contentid = c.contentid OR
p.contentid = c.contentid;

and if the table persusercontentassoc is empty no rows are returned. However, if i populate this table i get meaningful data. So what i'm asking is if any one table in a select contains no data will the select always return no rows ?

Thanks,

Gavin

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Received on Thu May 16 2002 - 00:08:22 CDT

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