If I define a custom SQL function: FormatMyString(StringToFormat, Format)

Then call it in this SQL:

SELECT * FROM MyTable
WHERE MyField = FormatMyString('Testing', 'X')

Will it execute FormatMyString just once, at the beginning of the query, or
will it do it for every record in the table?  Obviously if it is executing
for every record that will be dramatically slower, especially if MyField is
indexed.

Thanks,

Robert.

Robert


Every row in the table.

Roy Lambert

Robert,

<< Will it execute FormatMyString just once, at the beginning of the query,
or will it do it for every record in the table?  Obviously if it is
executing for every record that will be dramatically slower, especially if
MyField is indexed. >>

As long as you only pass it constant values, then it will only execute it
once.  If you pass it a column, then DBISAM will be forced to execute it
once for every record in the table.

--
Tim Young
Elevate Software
www.elevatesoft.com

"Tim Young [Elevate Software]" <timyoung@elevatesoft.com> wrote in message
news:8ED1AF3D-185F-4410-A809-234F532056D6@news.elevatesoft.com...
> Robert,
>
> << Will it execute FormatMyString just once, at the beginning of the
> query, or will it do it for every record in the table?  Obviously if it is
> executing for every record that will be dramatically slower, especially if
> MyField is indexed. >>
>
> As long as you only pass it constant values, then it will only execute it
> once.  If you pass it a column, then DBISAM will be forced to execute it
> once for every record in the table.

Thank you Tim, that's exactly what I was hoping you would say.