Test Query before executing

Question

Hello everyone,
I am write my final exam and I have to use oracle as the database and php as the GUI - programming - language.
Image this situation:
- Webform with 3 Textfields (names are a,b,c)
I have a table let's say mydata
mydata | value1 | value2 | value3
And I have defined some integrities like
value1.length >= 5
value2.length <= 5
value3.length >= 5 and value3.length <= 10
Now I want as soon sobody presses the submit button at the formular, the input-data should be checked. Right now I check them with PHP and as soon as an error occure, I return to the form with some error message.
I know, that is not the correct way, because if I check the data with PHP I don't need to create integrities at oracle.
Is there a way to check a query before exceuting? PHP creates three
querys, tests them all, and as soon there are no errors, then php calls the final
exceute querys.
My english is really bad, hopefully you get what I mean.
Thanks a lot
Hauke
PS.: I know I could update / insert all three values at the same time and it won't update / insert anything if one error occures, but in my program a form inserts / updates data from different tables at the same time
Message was edited by:
user584520

Answer 1

Hey,
so basicly what I what to do is to iterate through an array with sql - statements.
---- PHP ARRAY ----
update table1 set x=21 where id=1;
update table2 set y=333 where id=2;
---- PHP ARRAY ----
Now, I want to make sure, that all statements are correct for the oracle intergrity BEFORE the data will update.
In other words, all the querys should be tested and only if all tests are correct, then
it sould do the update - commands.
In case it's still not clear lets say you have a webform for changing your personal data. One field for your email-address and one for you lastname. I have oracle constraints to validate the email-address and another for validate the length of lastname. Also lets consider the email-address and lastname are not in the same table. What I have to do is something like
update CONTACTS set email='test' where id=1;
and
update ADDRESS set lastname='somebody' where id=1;
If I put both querys in one array and iterate thought it, the first element will cause an error because of the violation of constraints for email-address, the second one will be fine. So after iterating thought the array the lastname has changed, but the email is still the old one.
So the only way is the check all statements before executing them, but I have no idea if there is a possibility to do something like that.
Thanks again ;-)
Hauke