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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Dynamic SQL: where do you draw the line?
Thomas,
IMHO You probably picked up a BAD example to make your point. Yes I agree with you, but here the table is unknown, which would make this a Dynamic_sql of type 4 or 3?). in this case you are constructing whole statement dynamically.
Also it seems user developers are sending a string of numbers separated by space, which is replaced by semicolon to make a dynamic IN List. This might be the weekenss, Send them a URL to Asktom site and show them how to convert inlists into a table for max flexibility in the code.
You could, OTOH run some quick tests on this code and another where you have one delete statement per table and use 10046 event to show them what impact it has on the database. I hate long if-then-else structures too.
ps: if you want to break this code, send in p_site_guid value as '1,2' and watch the fun. In case of dynamic sql like this (and especially if it is coming from web), have your developers learn about sql-injecting techniques ... you _must_ validate input against a KNOWN set of values before using them. You _must_ also reject all unknowns with appropriate feedback.
Raj
-----Original Message-----
Sent: Wednesday, June 25, 2003 10:05 AM
To: Multiple recipients of list ORACLE-L
I've been fighting an ongoing war with our ecommerce developers, who are
inordinately fond of writing
dynamic SQL code that neglects to incorporate bind variables. Researching
AskTom I've
found and utilized different techniques to force bind variables into these
dynamic SQL queries,
including the use of application contexts, object types, etc.
However, I'm wondering if I'm making things worse, essentially providing
them with band-aids, when I should
be forcing them to change the way they code.
Consider the sample code below (which is a relatively simple example), which
is a generic DELETE statement
generator.
In this situation, the programmers claim the following code is good
programming practice, promotes
ease of maintenance, less buggy, and promotes code reusability (their
definition of reusability is a bit
different from mine).
I disagreed with them -- not only is this code not reusable at all, with the
parsing overhead consequences,
it's also harder to debug and tune for performance, due to all the
permutations that needs to be tested.
My take was that they be far better off writing a simple static DELETE
statement for each table.
Their rejoinder -- it's not worth writing lots of redundant code at the
expense of 'minimal' gains in
performance. Now, this code *could* be rewritten to use the SYS_CONTEXT
function on the p_object_id
and p_site_guid to force a bind variable on those two conditions, but the IN
condition with respect to the
p_asset_guid would be more problematic. However, I don't feel we should
have to be resorting to such measures
to get this code to using bind variables.
So, I'm at the point of denying such code to be migrated to production. I
recognize that there
are situations where there is a legitimate need for dynamic SQL, but the SQL
has to be written w/o catenating
literal SQL -- and if it can't -- they need to go back to square one.
Opinions? I'm curious -- do you have policies/standards with respect to dynamic SQL?
CREATE OR REPLACE PROCEDURE test
(
p_Asset_Guid IN VARCHAR2, p_Object_Id IN VARCHAR2, p_Object_Definition IN VARCHAR2, p_Site_Guid IN VARCHAR2, p_result IN OUT VARCHAR2
) AS
strTableName VARCHAR2(100);
strWhere VARCHAR2(100);
strQuery LONG;
BEGIN
IF p_Object_Definition = 'PRODUCT'
THEN
strTableName := ' TNE.GPD_PRODUCT_ASSET '; strWhere := ' MODEL_NO ';
OR p_Object_Definition = 'CHARACTERISTIC'
strTableName := ' TNE.GPD_CARACTERISTIC_ASSET '; strWhere := ' CARACTERISTIC_ID ';
strTableName := ' TNE.GPD_CATEGORY_ASSET '; strWhere := ' CATEGORY_GUID ';
strTableName := ' TNE.GPD_VALUE_ASSET '; strWhere := ' VALUE_ID ';
strTableName := ' TNE.GPD_PRODUCT_NODE_ASSET '; strWhere := ' PRODUCT_NODE_GUID ';
strTableName := ' TNE.GPD_CARAC_GROUP_ASSET '; strWhere := ' CARAC_GROUP_GUID ';
execute immediate strQuery;
p_result := '1';
RETURN;
END; --------------------------------------------Jeffery D Thomas
Email: [EMAIL PROTECTED]
Indy DBA Master Documentation available at: http://gkmqp.tce.com/tis_dba
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Thomas Jeff INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). ********************************************************************This e-mail message is confidential, intended only for the named recipient(s) above and may contain information that is privileged, attorney work product or exempt from disclosure under applicable law. If you have received this message in error, or are not the named recipient(s), please immediately notify corporate MIS at (860) 766-2000 and delete this e-mail message from your computer, Thank you.*********************************************************************2Received on Wed Jun 25 2003 - 12:24:37 CDT
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