An Example For Connecting, Looping, Querying and Displaying records in Pro*C/C++

/*


*  example1.pc
 *
 *  Prompts the user for an employee number,
 *  then queries the emp table for the employee's
 *  name, salary and commission.  Uses indicator
 *  variables (in an indicator struct) to determine
 *  if the commission is NULL.
 *
 */

#include <stdio.h>
#include <string.h>


/* Define constants for VARCHAR lengths. */
#define     UNAME_LEN      20
#define     PWD_LEN        40

/* Declare variables. No declare section is needed if MODE=ORACLE.*/
VARCHAR     username[UNAME_LEN];  
/* VARCHAR is an Oracle-supplied struct */
varchar     password[PWD_LEN];    
/* varchar can be in lower case also. */
/*
Define a host structure for the output values of a SELECT statement.
*/
struct {
    VARCHAR   emp_name[UNAME_LEN];
    float     salary;
    float     commission;
} emprec;
/* 
Define an indicator struct to correspond to the host output struct. */
struct
{
    short     emp_name_ind;
    short     sal_ind;
    short     comm_ind;
} emprec_ind;

/*  Input host variable. */
int         emp_number;
int         total_queried;
/* Include the SQL Communications Area.
   You can use #include or EXEC SQL INCLUDE. */
#include <sqlca.h>

/* Declare error handling function. */
void sql_error();

main()
{
    char temp_char[32];

/* Connect to ORACLE--
 * Copy the username into the VARCHAR.
 */
    strncpy((char *) username.arr, "SCOTT", UNAME_LEN);
/* Set the length component of the VARCHAR. */
    username.len = strlen((char *) username.arr);
/* Copy the password. */
    strncpy((char *) password.arr, "TIGER", PWD_LEN);
    password.len = strlen((char *) password.arr);
/* Register sql_error() as the error handler. */
    EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--n");

/* Connect to ORACLE.  Program will call sql_error()
 * if an error occurs when connecting to the default database.
 */
    EXEC SQL CONNECT :username IDENTIFIED BY :password;
    printf("nConnected to ORACLE as user: %sn", username.arr);
/* Loop, selecting individual employee's results */
    total_queried = 0;
    for (;;)
    {
/* Break out of the inner loop when a
 * 1403 ("No data found") condition occurs.
 */
        EXEC SQL WHENEVER NOT FOUND DO break;
        for (;;)
        {
            emp_number = 0;
            printf("nEnter employee number (0 to quit): ");
            gets(temp_char);
            emp_number = atoi(temp_char);
            if (emp_number == 0)
                break;
            EXEC SQL SELECT ename, sal, NVL(comm, 0)
                INTO :emprec INDICATOR :emprec_ind
                FROM EMP
                WHERE EMPNO = :emp_number;
/* Print data. */
            printf("nnEmployeetSalaryttCommissionn");
            printf("--------t------tt----------n");
/* Null-terminate the output string data. */
            emprec.emp_name.arr[emprec.emp_name.len] = '';
            printf("%-8st%6.2ftt",
                emprec.emp_name.arr, emprec.salary);
            if (emprec_ind.comm_ind == -1)
                printf("NULLn");
            else
                printf("%6.2fn", emprec.commission);

            total_queried++;
        }  /* end inner for (;;) */
        if (emp_number == 0) break;
        printf("nNot a valid employee number - try again.n");
    } /* end outer for(;;) */

    printf("nnTotal rows returned was %d.n", total_queried); 
    printf("nG'day.nnn");

/* Disconnect from ORACLE. */
    EXEC SQL COMMIT WORK RELEASE;
    exit(0);
}
void sql_error(msg)
char *msg;
{
    char err_msg[128];
    int buf_len, msg_len;

    EXEC SQL WHENEVER SQLERROR CONTINUE;
    printf("n%sn", msg);
    buf_len = sizeof (err_msg);
    sqlglm(err_msg, &buf_len, &msg_len);
    if (msg_len > buf_len)
    msg_len = buf_len;
    printf("%.*sn", msg_len, err_msg);
    EXEC SQL ROLLBACK RELEASE;
    exit(1);
}