RE: SQL question

From: Jamadagni, Rajendra <Rajendra.Jamadagni_at_espn.com>
Date: Fri, 7 May 2004 10:19:23 -0400
Message-ID: <A186CBDC8B1D61438BC50F1A77E91F73075BD6BB@xchgbrsm1.corp.espn.pvt>

Does select count(*) from test2 comes back with 3 rows? If so, this is classic Cartesian join. You have a join in FROM clause but no join clause in WHERE ...

Raj

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Rajendra dot Jamadagni at nospamespn dot com=20 All Views expressed in this email are strictly personal.=20 select standard_disclaimer from company_requirements;=20 QOTD: Any clod can have facts, having an opinion is an art !

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mike Schmitt Sent: Thursday, May 06, 2004 5:16 PM
To: oracle-l_at_freelists.org
Subject: SQL question=20

I was messing around with SQL, something that I am not very good with, when I ran into something I felt was strange. The SQL from both statements can be seen below, along with their execution plans. I do not quit understand why the 2nd query came back with 3 rows. I know its from user error, but shouldn't Oracle just ignore the test1 table in the second query?

SQL> select a.first_name from test2 a where a.id_number =3D 2; FIRST_NAME

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tom

SQL> select a.first_name from test2 a , test1 c where a.id_number =3D = 2;
FIRST_NAME

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tom
tom
tom

Execution Plan (1st statement)

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    0 SELECT STATEMENT Optimizer=3DCHOOSE     1 0 TABLE ACCESS (FULL) OF 'TEST2' Execution Plan (2nd statement)

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    0 SELECT STATEMENT Optimizer=3DCHOOSE     1 0 NESTED LOOPS

    2    1     TABLE ACCESS (FULL) OF 'TEST1'
    3    1     TABLE ACCESS (FULL) OF 'TEST2'







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Received on Fri May 07 2004 - 09:17:24 CDT