How can I control which field are being updated?

[Elivaldo]

For example:

Code: Select all

SELECT id, name, salary, ‘n’ as modified FROM employees

If I change the fields SALARY and MODIFIED I would receive the error “Unknown column MODIFIED in field list”

OK. One solution would be the use of SQLUpdate property, specifying the sentence for update:

Code: Select all

UPDATE employees SET name = x, salary = y WHERE id = z

But… this implies that the field NAME would be updated even if the only field really changed is SALARY. And this could lead to problem. Imagine that, at the same time, ComputerA changes the field NAME and ComputerB changes the field SALARY. The data from the last computer to apply would prevail.

Could anyone please help me?

[davidmarcus]

Not sure I understand the question. If you have multiple clients updating the same data, you need some form of locking. There are various ways to do this.

[Elivaldo]

Thanks, David. Putting it simpler: Is there a way to tell TMyQuery not do update a certain field?

[davidmarcus]

I don't know. I usually use TMyCommand to do updates. I don't know what TMyQuery can do.

[Elivaldo]

Ok, David. Thanks.

[pavelpd]

Hey,
Thanks for contacting us!

Kindly note, that we were unable to reproduce the "Unknown column MODIFIED in field list" error you mentioned based on the data you provided.
So could please compose and send us an sample application reproducing the error you have specified with all necessary DDL and DML scripts to create and populate database objects.
You can send all the needed samples via the e-support form: https://www.devart.com/company/contactform.html

Also, please send us the exact list of steps (actions) which leading to the error you indicated.
You can create and send us the screenshot demonstrating the issue.

Additionally, could you please clarify some additional information:
- What version of MyDAC do you have;
- What version of RadStudio;
- What version of the database;