在Oracle 8i中,往往会出现要在存储过程中运行操作系统命令的情况.一般来说,利用Oracle Enterprise Manager设定作业时可以达到这个目的.但是由于OEM在设定作业缺乏灵活性,设定的作业的参数是固定的.在实际应用当中往往需要在SQL语句当中运行需要随时运行操作系统命令.Oracle 8i没有直接运行OS命令的语句,我们可以利用DBMS_PIPE程序包实现这一要求. |
DBMS_PIPE通过创建管道,可以让至少两个进程进行通信.Oracle的管道与操作系统的管道在概念上有相同的地方,但是在实现机制不同. |
1 创建一个程序包,姑且起名叫DAEMON,SQL语句如下: |
CREATE OR REPLACE PACKAGE BODY daemon AS |
/*execute_system是实现运行os命令的函数*/ |
FUNCTION execute_system(command VARCHAR2, |
timeout NUMBER DEFAULT 10) |
pipe_name := DBMS_PIPE.UNIQUE_SESSION_NAME; |
DBMS_PIPE.PACK_MESSAGE('SYSTEM'); |
DBMS_PIPE.PACK_MESSAGE(pipe_name); |
DBMS_PIPE.PACK_MESSAGE(command); |
status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout); |
RAISE_APPLICATION_ERROR(-20010, |
'Execute_system: Error while sending. Status = ' || status); |
status := DBMS_PIPE.RECEIVE_MESSAGE(pipe_name, timeout); |
RAISE_APPLICATION_ERROR(-20011, |
'Execute_system: Error while receiving. |
DBMS_PIPE.UNPACK_MESSAGE(result); |
RAISE_APPLICATION_ERROR(-20012, |
'Execute_system: Done not received.'); |
DBMS_PIPE.UNPACK_MESSAGE(command_code); |
DBMS_OUTPUT.PUT_LINE('System command executed. result = ' || |
PROCEDURE stop(timeout NUMBER DEFAULT 10) IS |
DBMS_PIPE.PACK_MESSAGE('STOP'); |
status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout); |
RAISE_APPLICATION_ERROR(-20030, |
'stop: error while sending. status = ' || status); |
通过Sql*Plus运行以上语句,将为当前用户创建daemon程序包. |
2 创建在OS上运行的守护进程,监听由上面的daemon程序包发来的要求执行os命令的语句.以下Pro*C的代码,必须由pro*c先进行预编译. |
EXEC SQL BEGIN DECLARE SECTION; |
char *uid = "scott/tiger";/*在这个地方改为你自己访问的用户,密码,服务名*/ |
EXEC SQL END DECLARE SECTION; |
EXEC SQL WHENEVER SQLERROR CONTINUE; |
sqlglm(msg_buffer, &buffer_size, &msg_length); |
printf("Daemon error while connecting:/n"); |
printf("%.*s/n", msg_length, msg_buffer); |
printf("Daemon quitting./n"); |
EXEC SQL WHENEVER SQLERROR CONTINUE; |
sqlglm(msg_buffer, &buffer_size, &msg_length); |
printf("Daemon error while executing:/n"); |
printf("%.*s/n", msg_length, msg_buffer); |
printf("Daemon continuing./n"); |
EXEC SQL WHENEVER SQLERROR DO connect_error(); |
printf("Daemon connected./n"); |
EXEC SQL WHENEVER SQLERROR DO sql_error(); |
printf("Daemon waiting.../n"); |
:status := DBMS_PIPE.RECEIVE_MESSAGE('daemon'); |
DBMS_PIPE.UNPACK_MESSAGE(:command); |
command.arr[command.len] = '/0'; |
IF (!strcmp((char *) command.arr, "STOP")) |
printf("Daemon exiting./n"); |
ELSE IF (!strcmp((char *) command.arr, "SYSTEM")) |
DBMS_PIPE.UNPACK_MESSAGE(:return_name); |
DBMS_PIPE.UNPACK_MESSAGE(:value); |
value.arr[value.len] = '/0'; |
printf("Will execute system command '%s'/n", value.arr); |
status = system(value.arr); |
DBMS_PIPE.PACK_MESSAGE('done'); |
DBMS_PIPE.PACK_MESSAGE(:status); |
:status := DBMS_PIPE.SEND_MESSAGE(:return_name); |
("Daemon error while responding to system command."); |
printf(" status: %d/n", status); |
("Daemon error: invalid command '%s' received./n", |
printf("Daemon error while waiting for signal."); |
printf(" status = %d/n", status); |
EXEC SQL COMMIT WORK RELEASE; |
以上代码起名为daemon.pc,用proc预编译: |
proc iname=daemon.pc userid=用户名/密码@服务名 sqlcheck=semantics |
得到daemon.c,在用c进行编译,注意在NT上要把orasql8.lib加上,否则编译通过,连接没法通过. |
3 在服务器上运行daemon.exe |
|
SQL> execute :rv := DAEMON.EXECUTE_SYSTEM('ls -la'); |
SQL> execute :rv := DAEMON.EXECUTE_SYSTEM('dir'); |
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