[Lazarus] Using parameters with sqldb

[Joost van der Sluis]

On Tue, 2009-09-29 at 13:17 +0200, JoshyFun wrote:
> Hello waldo,
> 
> Tuesday, September 29, 2009, 6:32:22 AM, you wrote:
> 
> >> .ParamByname('filtro').AsString:='TESTE%';
> >> 
> >> .Value is not a good friend.
> 
> wk> then why does it exist if not usable?? :? :( 
> 
> It is usable, but as it involves variants some conversions could
> happend in an unexpected way. In fact .value is the only way I know to
> set the a field to NULL (variant value).

.Clear will also do that

> If filtro was a INTEGER field this code:
> 
> .ParamByname('filtro').Value:='1234';
> 
> what should it do ? Raise an error or convert the '1234' to 1234 ?

If you really want to use .value, you have to set the right paramkind,
so that it knows what type of value it is. (integer, string, bcd etc.)