From: | Ivo Simicevic <ivo(at)ultra(dot)hr> |
---|---|
To: | pgsql-interfaces(at)postgreSQL(dot)org |
Subject: | Re: a couple of newbie question |
Date: | 2000-04-16 21:03:12 |
Message-ID: | 20000416230312.A1117@ultra.hr |
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Thread: | |
Lists: | pgsql-interfaces |
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.
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