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. 下面介绍实现具体步骤: 1 创建一个程序包,姑且起名叫DAEMON,SQL语句如下: /*创建daemon程序包*/ 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) RETURN NUMBER IS status NUMBER; result VARCHAR2(20); command_code NUMBER; pipe_name VARCHAR2(30); BEGIN pipe_name := DBMS_PIPE.UNIQUE_SESSION_NAME; DBMS_PIPE.PACK_MESSAGE('SYSTEM'); DBMS_PIPE.PACK_MESSAGE(pipe_name); DBMS_PIPE.PACK_MESSAGE(command); /*向daemon管道发送表示命令的字符*/ status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout); IF status <> 0 THEN RAISE_APPLICATION_ERROR(-20010, 'Execute_system: Error while sending. Status = ' || status); END IF; status := DBMS_PIPE.RECEIVE_MESSAGE(pipe_name, timeout); IF status <> 0 THEN RAISE_APPLICATION_ERROR(-20011, 'Execute_system: Error while receiving. Status = ' || status); END IF; /*获取返回结果*/ DBMS_PIPE.UNPACK_MESSAGE(result); IF result <> 'done' THEN RAISE_APPLICATION_ERROR(-20012, 'Execute_system: Done not received.'); END IF; DBMS_PIPE.UNPACK_MESSAGE(command_code); DBMS_OUTPUT.PUT_LINE('System command executed. result = ' || command_code); RETURN command_code; END execute_system; /*stop是让daemon停止*/ PROCEDURE stop(timeout NUMBER DEFAULT 10) IS status NUMBER; BEGIN DBMS_PIPE.PACK_MESSAGE('STOP'); status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout); IF status <> 0 THEN RAISE_APPLICATION_ERROR(-20030, 'stop: error while sending. status = ' || status); END IF; END stop; END daemon; 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. #include #include EXEC SQL INCLUDE SQLCA; 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*/ int status; VARCHAR command[20]; VARCHAR value[2000]; VARCHAR return_name[30]; EXEC SQL END DECLARE SECTION; void connect_error() { char msg_buffer[512]; int msg_length; int buffer_size = 512; 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"); exit(1); void sql_error() { char msg_buffer[512]; int msg_length; int buffer_size = 512; 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"); } main() { EXEC SQL WHENEVER SQLERROR DO connect_error(); EXEC SQL CONNECT :uid; printf("Daemon connected.\n");
EXEC SQL WHENEVER SQLERROR DO sql_error(); printf("Daemon waiting...\n"); while (1) { EXEC SQL EXECUTE BEGIN /*接收deamon发来的字符*/ :status := DBMS_PIPE.RECEIVE_MESSAGE('daemon'); IF :status = 0 THEN /*取出字符*/ DBMS_PIPE.UNPACK_MESSAGE(:command); END IF; END; END-EXEC; IF (status == 0) { command.arr[command.len] = '\0'; /*如果是stop,该进程就退出*/ IF (!strcmp((char *) command.arr, "STOP")) { printf("Daemon exiting.\n"); break; }
ELSE IF (!strcmp((char *) command.arr, "SYSTEM")) { EXEC SQL EXECUTE BEGIN DBMS_PIPE.UNPACK_MESSAGE(:return_name); DBMS_PIPE.UNPACK_MESSAGE(:value); END; END-EXEC; value.arr[value.len] = '\0'; printf("Will execute system command '%s'\n", value.arr); /*运行os命令*/ status = system(value.arr); EXEC SQL EXECUTE BEGIN DBMS_PIPE.PACK_MESSAGE('done'); DBMS_PIPE.PACK_MESSAGE(:status); :status := DBMS_PIPE.SEND_MESSAGE(:return_name); END; END-EXEC;
IF (status) { printf ("Daemon error while responding to system command."); printf(" status: %d\n", status); } } ELSE { printf ("Daemon error: invalid command '%s' received.\n", command.arr); } } ELSE { printf("Daemon error while waiting for signal."); printf(" status = %d\n", status); } } EXEC SQL COMMIT WORK RELEASE; exit(0); }
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