125 lines
3.2 KiB
C
125 lines
3.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <libpq-fe.h>
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static void
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exit_nicely(PGconn *conn)
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{
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PQfinish(conn);
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exit(1);
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}
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int
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main(int argc, char **argv)
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{
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const char *conninfo;
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PGconn *conn;
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PGresult *res;
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int nFields;
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int i,
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j;
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printf("main() Started...\n");
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/*
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* If the user supplies a parameter on the command line, use it as the
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* conninfo string; otherwise default to setting dbname=postgres and using
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* environment variables or defaults for all other connection parameters.
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*/
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if (argc > 1){
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printf("main() argv[1]: %s\n", argv[1]);
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conninfo = argv[1];
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}else{
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conninfo = "dbname = postgres";
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}
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/* Make a connection to the database */
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conn = PQconnectdb(conninfo);
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if(conn==NULL){
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printf("main() connection object NOT available\n");
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}else{
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printf("main() connection object available\n");
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}
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/* Check to see that the backend connection was successfully made */
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if (PQstatus(conn) != CONNECTION_OK){
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fprintf(stderr, "Connection to database failed: %s",
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PQerrorMessage(conn));
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exit_nicely(conn);
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}else{
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printf("main() Connection to database succeded\n");
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}
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/*
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* Our test case here involves using a cursor, for which we must be inside
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* a transaction block. We could do the whole thing with a single
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* PQexec() of "select * from pg_database", but that's too trivial to make
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* a good example.
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*/
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/* Start a transaction block */
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res = PQexec(conn, "BEGIN");
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if (PQresultStatus(res) != PGRES_COMMAND_OK)
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{
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fprintf(stderr, "BEGIN command failed: %s", PQerrorMessage(conn));
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PQclear(res);
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exit_nicely(conn);
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}
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/*
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* Should PQclear PGresult whenever it is no longer needed to avoid memory
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* leaks
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*/
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PQclear(res);
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/*
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* Fetch rows from pg_database, the system catalog of databases
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*/
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res = PQexec(conn, "DECLARE myportal CURSOR FOR select * from pg_database");
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if (PQresultStatus(res) != PGRES_COMMAND_OK)
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{
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fprintf(stderr, "DECLARE CURSOR failed: %s", PQerrorMessage(conn));
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PQclear(res);
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exit_nicely(conn);
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}
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PQclear(res);
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res = PQexec(conn, "FETCH ALL in myportal");
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if (PQresultStatus(res) != PGRES_TUPLES_OK)
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{
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fprintf(stderr, "FETCH ALL failed: %s", PQerrorMessage(conn));
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PQclear(res);
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exit_nicely(conn);
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}
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/* first, print out the attribute names */
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nFields = PQnfields(res);
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for (i = 0; i < nFields; i++)
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printf("%-15s", PQfname(res, i));
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printf("\n\n");
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/* next, print out the rows */
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for (i = 0; i < PQntuples(res); i++)
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{
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for (j = 0; j < nFields; j++)
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printf("%-15s", PQgetvalue(res, i, j));
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printf("\n");
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}
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PQclear(res);
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/* close the portal ... we don't bother to check for errors ... */
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res = PQexec(conn, "CLOSE myportal");
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PQclear(res);
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/* end the transaction */
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res = PQexec(conn, "END");
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PQclear(res);
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/* close the connection to the database and cleanup */
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PQfinish(conn);
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printf("main() Done.\n");
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return 0;
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}
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