[Qt-interest] QSqlRecord population error checking

[Israel Brewster]

On Dec 10, 2009, at 2:20 PM, Robert Hairgrove wrote:

> Israel Brewster wrote:
>> What is the best way to do error checking when populating a  
>> QSqlRecord
>> with data? Or, a slightly different question that might solve the  
>> first,
>> what is the best way to add and populate a new row on a  
>> QSqlTableModel?
>> [snip]
>> At the moment what I am doing is
>> after each setValue call, I do an inverse value call and make sure  
>> the
>> return is what I just set. This seems rather kludgy, however. Is  
>> there a
>> better way?
>
> There is definitely a "better way", but it involves a rethink on the
> database side of things. The danger that "someone" will change a  
> column
> name, or a constraint such as changing a column allowing NULLs to NOT
> NULL, is very real and can cause major headaches on the application  
> side
> of things.
>
> The best (and only) solution that I know of is to grant ordinary users
> (i.e. non-DBA users) only SELECT and EXECUTE permissions on the  
> database
> and do any DML (i.e. updates, inserts and deletes) through stored
> procedures.

Agreed. Unfortunately as my application gets distributed to the  
general public, I'll obviously have no way of knowing or controlling  
things like what permissions ordinary users have, so I have to be  
prepared for as much as I can.

> If the database back-end doesn't support permissions or
> stored procedures (i.e. SQLite or MS-Access) then a lot of work has to
> be done on the application side to ensure database consistency.
>
> What is/are your supported back-end RDBMS?

SQLite for local installs, PostgreSQL or MySQL for larger installs.  
Thankfully Qt makes the distinction mostly transparent. On the  
downside, that also means that I am stuck with a back-end that doesn't  
support stored procedures or permissions, so I have to program for it.

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-----------------------------------------------
Israel Brewster
Computer Support Technician II
Frontier Flying Service Inc.
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7250 x293
-----------------------------------------------

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