Re: a couple of newbie question

On Sun, Apr 16, 2000 at 11:57:38AM -0700, Matthew Denny wrote:
>
> I know this question is probably fairly elementary, but I could not
> find the answer in the docs or mailing list archives. How does one handle
> NULL values in the embedded SQL interface? For example, if I have a
> statement:
>
> exec sql insert into test_table values(:foo, :x, :y)
>
> and foo represents a CHAR attribute (represented by a string in C) that I
> want to set to NULL, how do I go about doing this?

There are two ways :

exec sql insert into test_table values (NULL,:x,:y) or more properly

define indicator variable in DECLARE section and use it to insert null value
e.g.

EXEC SQL BEGIN DECLARE SECTION;
char foo[10];
int x;
int y;
int indicator;
EXEC SQL END DECLARE SECTION;
.....
indicator=-1;
EXEC SQL INSERT INTO test_table VALUES (:foo:indicator,:x,:y);

> Similarly, how do
> I tell that a value put into a variable by a fetch call is NULL or
> not?
>

You can do it the same way:

EXEC SQL SELECT foo,x,y
INTO :foo:indicator,:x,:y
......

and then check for indicator value.

GL

Ivo.