Sample Tables
Most programming examples in this guide use two sample database tables: DEPT and EMP. Their definitions follow:
CREATE TABLE DEPT
(DEPTNO NUMBER(2) NOT NULL,
DNAME VARCHAR2(14),
LOC VARCHAR2(13))
CREATE TABLE EMP
(EMPNO NUMBER(4) NOT NULL,
ENAME VARCHAR2(10),
JOB VARCHAR2(9),
MGR NUMBER(4),
HIREDATE DATE,
SAL NUMBER(7,2),
COMM NUMBER(7,2),
DEPTNO NUMBER(2))
Sample Data
Respectively, the DEPT and EMP tables contain the following rows of data:
DEPTNO DNAME LOC
------- ---------- ---------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ------- --------- ------ --------- ------ ------ -------
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 30
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81
950 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
________________________________________
Sample Program: A Simple Query
One way to get acquainted with Pro*C/C++ and embedded SQL is to study a program example. The program listed below is also available on-line in the file sample1.pc in your Pro*C/C++ demo directory.
The program connects to Oracle, then loops, prompting the user for an employee number. It queries the database for the employee's name, salary, and commission, displays the information, and then continues the loop. The information is returned to a host structure. There is also a parallel indicator structure to signal whether any of the output values SELECTed might be null.
You should precompile sample programs using the precompiler option MODE=ORACLE.
/*
* sample1.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: %s\n", 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, comm
INTO :emprec INDICATOR :emprec_ind
FROM EMP
WHERE EMPNO = :emp_number;
/* Print data. */
printf("\n\nEmployee\tSalary\t\tCommission\n");
printf("--------\t------\t\t----------\n");
/* Null-terminate the output string data. */
emprec.emp_name.arr[emprec.emp_name.len] = '\0';
printf("%-8s\t%6.2f\t\t",
emprec.emp_name.arr, emprec.salary);
if (emprec_ind.comm_ind == -1)
printf("NULL\n");
else
printf("%6.2f\n", 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("\n\nTotal rows returned was %d.\n", total_queried);
printf("\nG'day.\n\n\n");
/* 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%s\n", msg);
buf_len = sizeof (err_msg);
sqlglm(err_msg, &buf_len, &msg_len);
printf("%.*s\n", msg_len, err_msg);
EXEC SQL ROLLBACK RELEASE;
exit(1);
} |
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