Re: Help with returning data type - Mailing list pgsql-interfaces
From | Janet Borschowa |
---|---|
Subject | Re: Help with returning data type |
Date | |
Msg-id | D486606E7AD20947BDB7E56862E04C39BDC964@cvo1.cvo.roguewave.com Whole thread Raw |
In response to | Help with returning data type (Rudinei Dias <rudinei@unilasalle.edu.br>) |
List | pgsql-interfaces |
Hi, This isn't working because the char* you are getting back from PQgetvalue is either 't' or 'f' and so atol() fails. Also, you should not being calling PQclear on the PGresult until you are done with it and all the data it returned via PQgetvalue: i = 0; bytea = PQgetvalue(res, i, 0); //PQclear(res); // don't call this here because you are using bytea in the next call! strcpy(string, bytea); PQclear(res); // call it here! *var_len = strlen(string); return (unsigned char *) string; One other point, the table's schema should not use the datatype "name" as this is datatype is only for storage of internal catalog names. It would be much better to use "varchar(64)". ======================== Janet Borschowa Software Engineer, Database Products Rogue Wave Software, a QUOVADX(tm) Division (541) 753-1931 FAX: (541) 757-4630 mailto:borschow@roguewave.com http://www.roguewave.com -----Original Message----- From: Rudinei Dias [mailto:rudinei@unilasalle.edu.br] Sent: Wednesday, February 16, 2005 5:07 AM To: pgsql-interfaces@postgresql.org Subject: [INTERFACES] Help with returning data type Help with returning data type Hi. I'm in trouble with data type returns using libpq (PQgetvalue) see table definition - datname name NOT NULL, - encoding int4 NOT NULL, - datistemplate bool NOT NULL, - datallowconn bool NOT NULL, I codify with this way in C static long long_ret; static u_long ulong_ret; static unsigned char string[SPRINT_MAX_LEN]; static oid objid[MAX_OID_LEN];static struct counter64 c64; int i, index; char* bytea; * // 1 - THIS WORKS (retrieving varchar) * strcpy(query_string, "SELECT datname FROM pg_database limit 1 offset 0"); res = PQexec(conn, query_string); if (PQresultStatus(res) != PGRES_TUPLES_OK){ fprintf(stderr, "SELECT query failed [%s].\n", query_string); PQclear(res); return; } i = 0; bytea = PQgetvalue(res, i, 0); PQclear(res); strcpy(string, bytea); *var_len = strlen(string); return (unsigned char *) string; * // 2 - THIS WORKS (retrieving int4) * strcpy(query_string, "SELECT encoding FROM pg_database limit 1 offset 0"); res = PQexec(conn, query_string); if (PQresultStatus(res) != PGRES_TUPLES_OK){ fprintf(stderr, "SELECT query failed [%s].\n", query_string); PQclear(res); return; } i = 0; bytea = PQgetvalue(res, i, 0); index = atoi(bytea); PQclear(res); switch (index){ case 0: strcpy(string, "SQL_ASCII"); break; case 1: strcpy(string, "EUC_JP"); break; ... case 33:strcpy(string, "GB18030"); break; } *var_len = strlen(string); return (unsigned char *) string; * // 3 - THIS **DONT **WORK (retrieving bool) *** long_ret = 0; strcpy(query_string, "SELECT datistemplate FROM pg_database limit 1 offset 0"); res = PQexec(conn, query_string); if (PQresultStatus(res) != PGRES_TUPLES_OK){ fprintf(stderr, "SELECT query failed [%s].\n", query_string); PQclear(res); return; } i = 0; bytea = PQgetvalue(res, i, 0); long_ret = atol(bytea); return (unsignedchar *) &long_ret; How can I retrieve a bool data type (code 3)? How can I return for a string C data type (return (unsigned char *) &long_ret;) and the last question although working, its correct list code 1 and list code 2? anybody has code sample to share (mail me)? thank you for any help, my deadline paper is near and has proposed the open source MIB for postgresql database! thank you! ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
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