ODBC setup and simple examples in linux

sudo pacman -S unixodbc

sudo pacman -S myodbc   # mysql
sudo pacman -S psqlodbc # postgres
yaourt -S sqliteodbc    # sqlite

echo "select * from mytable" |isql -v psql-connector

echo "select * from mytable" | isql -v mariadb-connector

#include <stdio.h>
#include <sql.h>
#include <sqlext.h>

int main() {
    SQLHENV env;
    SQLCHAR driver[256];
    SQLCHAR attr[256];
    SQLSMALLINT driver_ret;
    SQLSMALLINT attr_ret;
    SQLUSMALLINT direction;
    SQLRETURN ret;

    /*
     *  Initializing lib vars
     */
    SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env);
    SQLSetEnvAttr(env, SQL_ATTR_ODBC_VERSION, (void *) SQL_OV_ODBC3, 0);

    direction = SQL_FETCH_FIRST;
    /*
     *  Get the list of available drivers.
     *  This is equivalent to odbcinst -q -d
     */
    while(SQL_SUCCEEDED(ret = SQLDrivers(env, direction, driver, sizeof(driver), &driver_ret,  attr, sizeof(attr), &attr_ret)))
    {
        direction = SQL_FETCH_NEXT;
        printf("%s - %s\n", driver, attr);
        if (ret == SQL_SUCCESS_WITH_INFO) printf("\tdata truncation\n");
    }

    SQLCHAR dsn[256];
    SQLCHAR desc[256];
    SQLSMALLINT dsn_ret;
    SQLSMALLINT desc_ret;


    /*
     * Get the list of available data sources.
     * This is equivalent to odbcinst -q -s
     */
    while(SQL_SUCCEEDED(ret = SQLDataSources(env, direction, dsn, sizeof(dsn), &dsn_ret, desc, sizeof(desc), &desc_ret)))
    {
        direction = SQL_FETCH_NEXT;
        printf("%s - %s\n", dsn, desc);
        if (ret == SQL_SUCCESS_WITH_INFO) printf("\tdata truncation\n");
    }
    return 0;
}

#include<stdio.h>
#include<sql.h>
#include<sqlext.h>
#include<exception>
#include<iostream>

#define NAME_LEN 50
#define ID_LEN 20

void show_error() {
    printf("SQL fetch Error");
}
/**
 * @brief error handling for SQL* functions
 */
void check_error(SQLRETURN ret_val, std::string act_str)
{
    switch (ret_val)
    {
        case SQL_SUCCESS:
        case SQL_SUCCESS_WITH_INFO:
            break;
        case SQL_NO_DATA:
            std::cerr << "end of data\n";
            break;
        default:
            throw std::runtime_error(act_str);
    }
}

int main() {
    SQLHENV henv;
    SQLHDBC hdbc;
    SQLHSTMT hstmt = 0;
    SQLRETURN retcode;
    SQLCHAR outstr[1024];
    SQLSMALLINT outstrlen;

    SQLCHAR szName[NAME_LEN], szID[ID_LEN];
    SQLLEN cbName = 0, cbID = 0;

    try {
        //Allocate environment handle
        retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
        check_error(retcode, "Allocate Environment Handle");
        //Set the ODBC version environment attribute
        retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER*)SQL_OV_ODBC3, 0);
        check_error(retcode, "Set ODBC version enviroment attribute");
        //Allocate connection handle
        retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
        check_error(retcode, "Allocate connection Handle");
        //Set login timeout to 5 seconds
        SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (SQLPOINTER)5, 0);
        check_error(retcode, "set login timeout attribute");

        /**
         * Connect to data source
         */
        retcode = SQLDriverConnect(hdbc, NULL, (SQLCHAR*)"DSN=mariadb-connector;", SQL_NTS, outstr, sizeof(outstr), &outstrlen, SQL_DRIVER_COMPLETE);
        check_error(retcode, "connect to the data source");

        //Allocate statement handle
        retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
        check_error(retcode, "allocate a statement handle");

        /**
         * statement to be executed.
         */
        retcode = SQLExecDirect (hstmt, (SQLCHAR *) "select * from mytable", SQL_NTS);
        check_error(retcode, "execute the statement");

        /**
         * Bind a column to a variable
         */
        retcode = SQLBindCol(hstmt, 1, SQL_C_CHAR, szName, NAME_LEN, &cbName);
        check_error(retcode, "bind 1 column to the statement");
        retcode = SQLBindCol(hstmt, 2, SQL_C_CHAR, szID, ID_LEN, &cbID);
        check_error(retcode, "bind 2 column to the statement");

        /**
         * fetch sql hstmt untill there is no data and print
         */
        for (int i=0 ; ; i++)
        {
            retcode = SQLFetch(hstmt);
            if(retcode == SQL_NO_DATA)break;
            else printf( "%d: %s %s %s\n", i + 1, szID, szName);
        }

        SQLCancel(hstmt);
        SQLFreeHandle(SQL_HANDLE_STMT, hstmt);

        SQLDisconnect(hdbc);
        SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
        SQLFreeHandle(SQL_HANDLE_ENV, henv);
    }
    catch(std::exception &e)
    {
        std::cerr << e.what() << std::endl;
        return 1;
    }
    return 0;
}