[fpc-pascal] How to clear the value of a field in a table using parameters?
Michael Van Canneyt
michael at freepascal.org
Fri Aug 30 15:45:44 CEST 2013
On Fri, 30 Aug 2013, silvioprog wrote:
> 2013/8/29 Michael Van Canneyt <michael at freepascal.org>
> On Thu, 29 Aug 2013, silvioprog wrote:
>
>
> Other interesting feature is the property EmptyAsNull:
>
> http://docwiki.embarcadero.com/VCL/XE/en/IBCustomDataSet.TIBStringField.EmptyAsNull
>
> It tests if field (ftString) is empty (f = ''), if yes, it set the field value to null (f.Clear).
>
>
> Apparently a IBX specific extension.
>
> I don't see the value of this. empty and null are different things.
>
> Michael.
>
>
> Some Delphi components (Zeos, JvDBEdit) have this option.
>
> Assuming this table:
>
> test
> id integer,
> name varchar(10) not null unique
>
> You can:
>
> id|name
> 1| <null>
> 2| <null>
>
> But:
>
> 1| <empty>
> 2| <empty> << error, unique key
>
> I implemented "EmptyAsNull" directly in my project. It is very useful. In my webpages, if the user clear a input, I send a
> null value to the table.
Good for you :)
Michael.
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