#include <stdio.h>
#include <stdlib.h>
#include "libpq-fe.h"   
int
main(int argc, char **argv){
    const char *conninfo;
    PGconn     *conn;      
    PGresult   *res;
    const char *sql = "select * from tbase";
    if (argc > 1){
        conninfo = argv[1];
    }else{
        conninfo = "dbname = postgres";           
    }
    conn = PQconnectdb(conninfo);    
    if (PQstatus(conn) != CONNECTION_OK){
        fprintf(stderr, "连接数据库失败: %s",PQerrorMessage(conn));              
    }else{    
        printf("连接数据库成功！\n");
    }                                
    res = PQexec(conn,sql);
    if(PQresultStatus(res) != PGRES_TUPLES_OK){
        fprintf(stderr, "插入数据失败: %s",PQresultErrorMessage(res)); 
    }else{
        printf("查询数据成功！\n");    
        int rownum = PQntuples(res) ;
        int colnum = PQnfields(res);
        for(int j = 0;j< colnum; ++j){
            printf("%s\t",PQfname(res,j));
        }
        printf("\n");
        for(int i = 0;i< rownum; ++i){
            for(int j = 0;j< colnum; ++j){
                printf("%s\t",PQgetvalue(res,i,j));
            }
            printf("\n");
        }
    }
    PQclear(res);
    PQfinish(conn);
    return 0;
}

编译

gcc -std=c99 -c -I /usr/local/install/tbase_pgxz/include/ select.c
gcc -o select select.o -L /usr/local/install/tbase_pgxz/lib/ -lpq

运行

./select "dbname=postgres port=15432"
#连接数据库成功！
#查询数据成功！
id      nickname
1       tbase
2       pgxz