RE: SQL question
- From: "Jamadagni, Rajendra" <Rajendra.Jamadagni@xxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 7 May 2004 10:19:23 -0400
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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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Mike Schmitt
Sent: Thursday, May 06, 2004 5:16 PM
To: oracle-l@xxxxxxxxxxxxx
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
------------------------------
tom
SQL> select a.first_name from test2 a , test1 c where a.id_number =3D =
2;
FIRST_NAME
------------------------------
tom
tom
tom
Execution Plan (1st statement)
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=3DCHOOSE
1 0 TABLE ACCESS (FULL) OF 'TEST2'
Execution Plan (2nd statement)
----------------------------------------------------------
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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