SQL question
- From: Mike Schmitt <mschmitt@xxxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Thu, 06 May 2004 16:16:01 -0500
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 = 2;
FIRST_NAME
------------------------------
tom
SQL> select a.first_name from test2 a , test1 c where a.id_number = 2;
FIRST_NAME
------------------------------
tom
tom
tom
Execution Plan (1st statement)
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 TABLE ACCESS (FULL) OF 'TEST2'
Execution Plan (2nd statement)
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 NESTED LOOPS
2 1 TABLE ACCESS (FULL) OF 'TEST1'
3 1 TABLE ACCESS (FULL) OF 'TEST2'
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