Обсуждение: Examples of using PQexecParams

I was looking for examples of using PQexecParams but all I found was
this: http://sepp.oetiker.ch/postgresql-8.2.3-ds/libpq-example.html

/* Convert integer value "2" to network byte order */
    binaryIntVal = htonl((uint32_t) 2);
/* Set up parameter arrays for PQexecParams */
    paramValues[0] = (char *) &binaryIntVal;
    paramLengths[0] = sizeof(binaryIntVal);
    paramFormats[0] = 1;        /* binary */
...
seems a bit convoluted.

In particular I was looking for an example of setting up a string
parameter for PQexecParams, assuming that is possible.

Daniel wrote:
> I was looking for examples of using PQexecParams but all I found was
> this: http://sepp.oetiker.ch/postgresql-8.2.3-ds/libpq-example.html
>
> /* Convert integer value "2" to network byte order */
>     binaryIntVal = htonl((uint32_t) 2);
> /* Set up parameter arrays for PQexecParams */
>     paramValues[0] = (char *) &binaryIntVal;
>     paramLengths[0] = sizeof(binaryIntVal);
>     paramFormats[0] = 1;        /* binary */
> ...
> seems a bit convoluted.
>
> In particular I was looking for an example of setting up a string
> parameter for PQexecParams, assuming that is possible.
>

strings don't need to be passed in binary, so its a lot simpler.

see example 30-3 on
http://www.postgresql.org/docs/current/static/libpq-example.html

    const char *paramValues[1];

   /* Here is our out-of-line parameter value */
    paramValues[0] = "joe's place";

    res = PQexecParams(conn,
                       "SELECT * FROM test1 WHERE t = $1",
                       1,       /* one param */
                       NULL,    /* let the backend deduce param type */
                       paramValues,
                       NULL,    /* don't need param lengths since text */
                       NULL,    /* default to all text params */
                       0);      /* ask for text results */

On Fri, Dec 4, 2009 at 1:47 PM, Daniel <danwgrace@gmail.com> wrote:
> I was looking for examples of using PQexecParams but all I found was
> this: http://sepp.oetiker.ch/postgresql-8.2.3-ds/libpq-example.html
>
> /* Convert integer value "2" to network byte order */
>    binaryIntVal = htonl((uint32_t) 2);
> /* Set up parameter arrays for PQexecParams */
>    paramValues[0] = (char *) &binaryIntVal;
>    paramLengths[0] = sizeof(binaryIntVal);
>    paramFormats[0] = 1;        /* binary */

check out libpqtypes (http://libpqtypes.esilo.com).  It does all the
binary stuff for you (which you don't need to to with PQexecParams).

with libpqtypes, you can do stuff like:
res = PQexecf(conn, "insert into foo values (%int4, %text)", 2, "test");

note: libpqtypes requires a patched libpq for client versions < 8.4

merlin

> check out libpqtypes (http://libpqtypes.esilo.com).  It does all the
> binary stuff for you (which you don't need to to with PQexecParams).
>

thanks, but how do you install it on Gentoo, there is no ebuild.