Help with parsing an UPDATE statement

Question

I am stuck and need help! The teacher has not gone over parsing with us
and it is not on his scheduled topics list. But, I am a person that likes to
scope out and learn new things. For our final project, we have to allow
updates, delete and inserts into the 5 main tables of the Premiere Products
database. I have done everything except for the updates. I can achieve
the updates of the entities by pretty much hardcoding them and that is
okay by the teacher, but I want to learn about parsing because Barbara
from this site mentioned this to me.
This is what I was able to write and I am getting errors:
CREATE OR REPLACE PROCEDURE updatecust_proc (
v_cust_num IN customera.cust_num%TYPE,
v_attributetoupdate VARCHAR2 ,
v_updatedvalue VARCHAR2 )
AS
e_invalidcustnum_error EXCEPTION;
BEGIN
v_isvalidcustnum := iscust(v_cust_num);
IF (v_isvalidcustnum = FALSE) THEN
RAISE e_invalidcustnum_error;
END IF;
PARSE(
'UPDATE customer
SET' | | v_attributetoupdate | | '=' | | v_updatedvalue | |
'WHERE cust_num =' | | v_cust_num
END;
EXCEPTION
WHEN e_invalidcustnum_error THEN
DBMS_OUTPUT.PUT_LINE('Cannot be updated. Invalid customer number');
END;
Any help would be useful. I went to the Oracle help site but their examples are a little too complicated for me to understand, plus, I am not using any C code.
Thanks in advance!
Bob

Answer 1

Now we are getting somewhere. Identifier 'PARSE' must be declared.
I again used the 'Search' link just above the forum posts and entered 'dbms_sql.parse' and got a short list of hits (as I suggested in my previous reply).
There is one with Barbara's name on it. It shows exactly how to do what you are trying to do. In particular note her code:
DBMS_SQL.PARSE
(cursor_name,
'UPDATE client SET '
| | v_column
| | ' = ' | | '''' | | v_new_data | | ''''
| | ' WHERE account_id = '
| | v_account_id,
DBMS_SQL.NATIVE);
Compare her PARSE statement to yours and you will see some major differences. The PARSE procedure is defined in the DBMS_SQL package and must be reference by DBMS_SQL.PARSE as Barbara shows.
In addition to dynamic SQL using the DBMS_SQL package Oracle 8i also supports the EXEC IMMEDIATE statement.
All of Oracle's documentation is available online via the 'Documentation' link on the left side of the OTN home page.
The 'Supplied PL/SQL Packages Reference' has a chapter for each package (including DBMS_SQL) and describes the procedures/functions in the package and how to use them.
The 'Application Developers Guide - Fundamentals' has chapters on 'processing SQL statements' and 'dynamic SQL' that go into some detail on performing dynamic sql.
Yes, Barbara's code uses a CURSOR. The DBMS_SQl package requires it and so does your code. Almost all SQL uses a CURSOR either implicitly or explicitly.
My comments are not, and were not, directed at you personally so I hope you don't take them that way.
Your latest reply has a lot of useful information in it.
1. 19/1 PLS-00201: identifier 'PARSE' must be declared. This is the explicit error message we need to help someone. We don't have to guess which error they are talking about. We can look it up in the MESSAGES manual if necessary. When someone says 'I get an error', or 'I get a PARSE error' we can only guess which error they are talking about.
In your reply you state that you looked at Barbara's code, she uses a cursor and you don't need a cursor. That is very useful information to someone trying to help you because it tells us two things: you are trying to find the answer for yourself (a lot of people just want someone to write the code for them) and it shows that you haven't made the connection between Barbara's example (which shows EXACTLY what you need to do) and your own code.
This is a public forum and I have found it useful to keep repeating certain suggestions.
For whatever reason many people still do not seem to realize that:
1. ALL of Oracle's documentation is available on-line via the 'Documentation' link on the left side of the OTN main page.
2. You can purchase (for about $50) a CD-ROM that has all of the Oracle documentation on it in both PDF and HTML format.
3. The 'search' link just above each discussion forum allows one to search any or all forums for topics, users, etc.
The above resources should be used by everyone.
Good luck!
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