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标题: pro*c的高手看过来 [打印本页]

作者: cups_book 时间: 2010-09-08 13:19
标题: pro*c的高手看过来
本帖最后由 cups_book 于 2010-09-08 14:20 编辑 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); if (msg_len > buf_len) msg_len = buf_len; printf("%.*s\n", msg_len, err_msg); EXEC SQL ROLLBACK RELEASE; exit(1); } 解释一下上面的函数蓝色部分，看起来很怪，看不懂。我改成： /* declare error handling function*/ void sql_error(char *msg) { char err_msg[128]; size_t 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); } 也是可以顺利编译的。 [oracle@Tux10M simpapp]$ proc parse=none iname=fetch.pc include=/u01/app/oracle/product/10.2.0/client_1/precomp/public Pro*C/C++: Release 10.2.0.1.0 - Production on Wed Sep 8 13:56:05 2010 Copyright (c) 1982, 2005, Oracle. All rights reserved. System default option values taken from: /u01/app/oracle/product/10.2.0/client_1/precomp/admin/pcscfg.cfg [oracle@Tux10M simpapp]$

作者: l2y3n2 时间: 2010-09-08 13:19
等于

void sql_error(char *msg)

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作者: cups_book 时间: 2010-09-08 13:20
标题: orcle的官方文档来的，是正式文档
Example Program: A Simple Query
One way to get acquainted with Pro*C/C++ and embedded SQL is to study a program example. The following program 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.

Precompile example 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, NVL(comm, 0)
            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);
if (msg_len > buf_len)
msg_len = buf_len;
printf("%.*s\n", msg_len, err_msg);
EXEC SQL ROLLBACK RELEASE;
exit(1);
}

作者: renxiao2003 时间: 2010-09-08 13:46
为什么不写在括号里，要写出来呢。C被ORACLE整得是乱七八糟的。

作者: cups_book 时间: 2010-09-08 13:49

为什么不写在括号里，要写出来呢。C被ORACLE整得是乱七八糟的。
renxiao2003 发表于 2010-09-08 13:46

对呵，我就是被它搞的一头雾水。

作者: cups_book 时间: 2010-09-08 13:50

等于
l2y3n2 发表于 2010-09-08 13:41

确认不？

作者: duolanshizhe 时间: 2010-09-08 14:06
不太懂帮顶啊呵呵呵

作者: cups_book 时间: 2010-09-08 14:21
回复 7# duolanshizhe

呵呵，对了，你研究出怎么查看pro*c的版本了吗？

作者: duolanshizhe 时间: 2010-09-08 14:30
proc --version

作者: l2y3n2 时间: 2010-09-08 16:03

确认不？
cups_book 发表于 2010-09-08 13:50

不确定，pro*c什么的不了解。

但是GCC是支持这种函数的声明方式的。

作者: longma_521 时间: 2010-09-08 22:46
两种写法一样，标准不一样，比较老的写法都是定义参数在外面。

作者: doni 时间: 2010-09-09 09:57
这个不算是Pro*C的问题，基本上是C的问题
两种写法是一样的

不过在pre-compile时，如果用parse=none的话，就可能必须写在外面了
比如：

void something ( some_val )
EXEC SQL BEGIN DECLARE SECTION;
int some_val;
EXEC SQL END DECLARE SECTION;
{
...
}

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当然，some_val在SQL中会用到，才须要这样做

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