From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200102131456.JAA24367@candle.pha.pa.us>
Subject: Re: C/C++ interface
In-Reply-To: <3A892433.879F40A0@dohle.com> "from Volker Paul at Feb 13, 2001
	01:10:27 pm"
To: Volker Paul <vpaul@dohle.com>
Date: Tue, 13 Feb 2001 09:56:27 -0500 (EST)
CC: pgsql-sql@postgresql.org
MIME-Version: 1.0
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Cursors and standard queries are pretty much the same, except the cursor
can control the rows returned.

> Hello,
> 
> in the C interface documentation there is an example using:
> 
>     res = PQexec(conn, "DECLARE mycursor CURSOR FOR select * from
> pg_database");
>     if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
>     {
>         fprintf(stderr, "DECLARE CURSOR command failed\n");
>         PQclear(res);
>         exit_nicely(conn);
>     }
>     PQclear(res);
>     res = PQexec(conn, "FETCH ALL in mycursor");
> 
> ...etc. So the statements are:
> 
> DECLARE mycursor CURSOR FOR select * from pg_database;
> FETCH ALL in mycursor;
> 
> What's the difference between this and simply doing:
> select * from pg_database;
> 
> I tried this in psql, the result seemed the same.
> 
> What I'm really using, however, is the C++ interface.
> Its documentation is not yet complete.
> There, too, I tried a version with and without cursor.
> The result seems to be the same, but returned int is always 0
> for the version without cursor, so I get no information whether
> the query succeeded. 
> 
> Is someone maintaining the C++ interface and its documentation?
> 
> 
> Thanks,
> 
> Volker Paul
> 


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