Обсуждение: Loading/Retrieving bytea fields?

Has anyone found some C code that shows how to load/extract data from a
bytea column?

thanks

Jerry

     Jerry LeVan writes

> Has anyone found some C code that shows how to load/extract data from a
> bytea column?

This works for me:

int size;
const char* contents;
PGresult* res;
res = PQexecParams(pgconn,
        "SELECT contents FROM tblob WHERE pkey=value",
        0, NULL,NULL,NULL,NULL,   /* no input parameters */
        1  /* output in binary format */ );

if (res && PQresultStatus(res)==PGRES_TUPLES_OK) {
  size = PQgetlength(res, 0, 0);
  contents = PQgetvalue(res, 0, 0);    /* binary representation */
}

I believe that you may also use the plain PQexec instead of PQexecParams,
but then you would have to call PQunescapeBytea() on the bytea column in the
results, so it's likely to be less efficient. I haven't tried that, though.

--
 Daniel
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