Ligação ODBC

/* Permite a ligação ODBC a uma BD */

// Apple Xcode
// gcc -lodbc main.c -o teste


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

int main (int argc, const char * argv[])
{
    // environment handle
    HENV the_henv = NULL;
    // connection handle
    HDBC the_hdbc = NULL;
    // statement handle
    HSTMT the_hstmt = NULL;

    // odbc
    UCHAR the_dsn[SQL_MAX_DSN_LENGTH] = "ODBC_CONNECTION_NAME";
    UCHAR* the_uid = NULL; // (unsigned char *) "login";
    UCHAR* the_password = NULL; // (unsigned char *) "password";

    // field var
    SDWORD the_cell_buffer; // buffer
    UCHAR the_column_a[255];
    UCHAR the_column_b[255];
    UCHAR the_column_c[255];

    // sql query
    UCHAR the_sql_string[] = "SELECT column_a, column_b, column_c FROM table";

    // SQLRETURN
    RETCODE the_retcode;

    // allocates an environment handle and associated resources
    SQLAllocEnv(&the_henv);
    // allocates a connection handle and associated resources within the environment identified by the input environment handle
    SQLAllocConnect(the_henv, &the_hdbc);

    // establishes connections to a driver and a data source
    the_retcode = SQLConnect(the_hdbc, the_dsn, SQL_NTS, the_uid, SQL_NTS, the_password, SQL_NTS);

    // after connection...
    if (the_retcode == SQL_SUCCESS || the_retcode == SQL_SUCCESS_WITH_INFO)
    {
        // allocates a new statement handle and associates it with the connection specified by the connection handle
        the_retcode = SQLAllocStmt(the_hdbc, &the_hstmt);
        // associates an SQL statement with the input statement handle provided
        the_retcode = SQLPrepare(the_hstmt, the_sql_string, sizeof(the_sql_string));
        // executes a statement that was successfully prepared using SQLPrepare() on the same statement handle
        the_retcode = SQLExecute(the_hstmt);

        if (the_retcode == SQL_SUCCESS || the_retcode == SQL_SUCCESS_WITH_INFO)
        {
            while (the_retcode == SQL_SUCCESS || the_retcode == SQL_SUCCESS_WITH_INFO)
            {
                // binds application data buffers to columns in the result set
                SQLBindCol(the_hstmt, 1, SQL_C_CHAR, the_column_a, sizeof(the_column_a), &the_cell_buffer);
                SQLBindCol(the_hstmt, 2, SQL_C_CHAR, the_column_b, sizeof(the_column_b), &the_cell_buffer);
                SQLBindCol(the_hstmt, 3, SQL_C_CHAR, the_column_c, sizeof(the_column_c), &the_cell_buffer);

                the_retcode = SQLFetch(the_hstmt);
                if (the_retcode != SQL_NO_DATA_FOUND)
                {
                    printf("%s %s %s\n", the_column_a, the_column_b, the_column_c);
                }
                else
                {
                    printf("...");
                }
            }
        }
        else
        {
            printf("erro: na construcao da consulta sql\n");
        }

        // process data
        if (the_retcode == SQL_SUCCESS || the_retcode == SQL_SUCCESS_WITH_INFO)
        {
            SQLCancel(the_hstmt);
            SQLFreeHandle(SQL_HANDLE_STMT, the_hstmt);
        }

        // free
        SQLFreeStmt(the_hstmt, SQL_DROP);
        SQLDisconnect(the_hdbc);
    }
    else
    {
        printf("erro: sem sucesso\n");
    }

    // free hEnv
    SQLFreeEnv(the_henv);

    // sleep windows (Sleep): ms; posix (sleep): seconds
    sleep(5);

    return 0;
}