Field update using a fieldname variable

> I have a variable which holds the name of a field on the current form,
> say field_name.  I'd like to be able to change the value of the field held in
> field_name.  What I'd like to do is something like:
>
> field_name = 'student_num';   /* where student_num is the name of a field */
> :field_name = '1000'; /* set the value of student_num to '1000' */
>
> This is an abuse of the 4GL name notation but I hope you see what I mean.
> The closest thing I've noticed is that expressions like
> 'clear field :field_name' are possible, but I guess this is really just a form
> of parameter passing.
>
> Is there an easy/any way to do this?

You could use a 3GL procedure.  Here's an example in C:

 void put_form( const char *form_name , const char *field_name
  , const char *value ) {
 #ifdef ARGS_FOR_ESQL
  exec sql BEGIN declare section ;
  char *form_name ;
  char *field_name ;
  char *value ;
  exec sql END declare section ;
 #endif

  exec frs PUTFORM :form_name ( :field_name = :value ) ;

  return ;

  }

In your 4GL code:

 field_name := 'student_num' ;
 callproc put_form( 'this_form' , field_name , '1000' ) ;

You will need to write a separate 3GL procedure for each of the C
datatypes: char, long, and double.  This should handle all of the
standard INGRES datatypes.

--Mark Jaeger
University of Chicago   phone: (312) 702-0328
Graduate School of Business    fax: (312) 702-0233
1101 East 58th Street, W309  email: cs_mj@gsbvax.uchicago.edu
Chicago, IL  60637-1511, USA         (internet)
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