Cursor Case statement

Question

Hello All
I hava a performance issue to perform. I have a procedure that takes some parameters on input. then i create a cursore using thoses parameters like this :
CREATE OR REPLACE PROCEDURE MY_PROC (vNoA varchar2, vNoB varchar2, vDatedeb DATE, vDateFin DATE, vInfo varchar2, vPID INTEGER)
IS
Cursor tickets is select NoA, NoB, STARTDATE, ELAPSED_TIME, SWITCH_ID
FROM MY_TABLE
WHERE (SUBSTR(NoA,-9)=SUBSTR(vNoA,-9) OR SUBSTR(NoB,-9)=SUBSTR(vNoB,-9)) AND STARTDATE between vDatedeb AND vDateFin;
begin ........end;
what i want to do is to skip the use of the OR in the cursor creation statement using this rule :
if vNaB is nul then the WHERE clause will look like :
WHERE SUBSTR(NoA,-9)=SUBSTR(vNoA,-9) AND STARTDATE between vDatedeb AND vDateFin
if vNaA is nul then the WHERE clause will look like :
WHERE SUBSTR(NoB,-9)=SUBSTR(vNoB,-9) AND STARTDATE between vDatedeb AND vDateFin
Else the clause stays the same
Any one have an idea
Thanks in advance
Best regards

Answer 1

You should avoid FOR LOOP single row processing where possible. It is one of the slowest methods of data processing. All your logic can be replaced with a statement like the following:
INSERT INTO TABLE2
        NoA
,       NoB
,       STARTDATE
,       ELAPSED_TIME
,       SWITCH_ID
,       PID
SELECT  NoA
,       NoB
,       TO_CHAR(STARTDATE,'DD/MM/YYYY HH24:MI:SS')
,       ELAPSED_TIME
,       SWITCH_ID
,       vPID
FROM    MY_TABLE
WHERE   (
                SUBSTR(NoB,-9) = SUBSTR(vNoB,-9)
        OR      SUBSTR(NoA,-9) = SUBSTR(vNoA,-9)
AND     STARTDATE BETWEEN vDatedev AND vDateFin;      In addition your query is running slow most likely because of the SUBSTR() function being applied to the NoA and NoB columns. In this case Oracle cannot use indexes. You may want to create a FUNCTION BASED INDEX on the NoA and NoB columns.
Edited by: Centinul on Feb 16, 2010 9:05 AM