開發子程序

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一：開發過程。

過程用於執行特定操作，可以指定輸入參數，也可以指定輸出參數。

1.建立過程帶有IN參數。不指定默認爲IN參數。

CREATE OR REPLACE PROCEDURE add_employee

(eno NUMBER,name VARCHAR2,sal NUMBER,job VARCHAR2 DEFAULT 'CLERK',dno NUMBER)

IS

  e_integrity EXCEPTION;

  PRAGMA EXCEPTION_INIT(e_integrity,-2291);

BEGIN

  INSERT INTO emp(empno,ename,sal,job,deptno)

  VALUES(eno,name,sal,job,dno);

EXCEPTION

 WHEN DUP_VAL_ON_INDEX THEN

  RAISE_APPLICATION_ERROR(-20000,'僱員號不能重複');

 WHEN e_integrity THEN

  RAISE_APPLICATION_ERROR(-20001,'部門號不存在');

END;

輸入重複僱員號：

exec add_employee(1111,'CLARK',2000,'MANAGER',10)

begin add_employee(1111,'CLARK',2000,'MANAGER',10); end;

ORA-20000: 僱員號不能重複自定義錯誤號

2. 建立過程帶有OUT參數

CREATE OR REPLACE PROCEDURE query_employee

(eno NUMBER,name OUT VARCHAR2,salary OUT NUMBER)

IS

BEGIN

 SELECT ename,sal INTO name,salary FROM emp

 WHERE empno=eno;

EXCEPTION

 WHEN NO_DATA_FOUND THEN

 RAISE_APPLICATION_ERROR(-20000,'僱員不存在');

END;

SQL> var name VARCHAR2(10)

SQL> var salary NUMBER

SQL> exec query_employee(7788,:name,:salary)

begin query_employee(7788,:name,:salary); end;

ORA-20000: 僱員不存在

ORA-06512: 在 "SYS.QUERY_EMPLOYEE", line 9

ORA-06512: 在 line 2

 

var name VARCHAR2(10)

SQL> var salary NUMBER

SQL> exec query_employee(7369,:name,:salary)

PL/SQL procedure successfully completed

name

---------

SMITH

salary

---------

3600

3.帶有IN OUT 參數

CREATE OR REPLACE PROCEDURE compute

(num1 IN OUT NUMBER,num2 IN OUT NUMBER)

IS

v1 NUMBER;

v2 NUMBER;

BEGIN

v1:=num1/num2;

v2:=MOD(num1,num2);

num1:=v1;

num2:=v2;

END;

SQL> var n1:=100 NUMBER

SQL> var n2:30 NUMBER

SQL> exec compute(:n1,:n2)

4.參數傳遞的三種方式

1.位置傳遞（如上）

2.名稱傳遞

CREATE OR REPLACE PROCEDURE add_dept

(dno NUMBER,dname VARCHAR2 DEFAULT NULL,loc VARCHAR2 DEFAULT NULL)

IS

BEGIN

INSERT INTO dept VALUES(dno,dname,loc);

EXCEPTION

WHEN DUP_VAL_ON_INDEX THEN

RAISE_APPLICATION_ERROR(-20000,'部門號不能重複');

END;

exec add_dept(dname=>'SALES',dno=>70);

3.混合傳遞

5.查看過程源代碼

SELECT text FROM user_source WHERE name='ADD_DEPT';

6.刪除過程

DROP PROCEDURE add_dept;

 

二：開發函數

函數用於返回特定數據，當經常需要使用SQL返回數據時可以定義函數

1.      函數：不帶參數

CREATE OR REPLACE FUNCTION get_user

 RETURN varchar2

 IS

  v_user VARCHAR2(100);

 BEGIN

  SELECT username INTO v_user FROM user_users;

  RETURN v_user;

END;

1.使用變量接受返回值

SQL> var v1 VARCHAR2(100)

SQL> exec :v1:=get_user

PL/SQL procedure successfully completed

v1

---------

SYS

2.    SQL語句調用函數

select get_user FROM dual;

 

2.建立函數：帶有IN參數

CREATE OR REPLACE FUNCTION get_sal(name IN VARCHAR2)

RETURN NUMBER

AS

v_sal emp.sal%TYPE;

BEGIN

SELECT sal INTO v_sal FROM emp

WHERE upper(ename)=upper(name);

RETURN v_sal;

EXCEPTION

WHEN NO_DATA_FOUND THEN

RAISE_APPLICATION_ERROR(-20000,'該僱員不存在');

END;

SQL> var sal number

SQL> exec :sal:=get_sal('smith')

3.  建立函數：帶有OUT參數

CREATE OR REPLACE FUNCTION get_into

(name VARCHAR2,title OUT VARCHAR2)

 RETURN VARCHAR2

 AS

 deptname dept.dname%TYPE;

BEGIN

 SELECT a.job,b.dname INTO title,deptname

 FROM emp a,dept b

 WHERE a.deptno=b.deptno

 AND upper(a.ename)=upper(name);

 RETURN deptname;

EXCEPTION

 WHEN NO_DATA_FOUND THEN

 RAISE_APPLICATION_ERROR(-20000,'該僱員不存在');

END;

var job varchar2(20)

var dname varchar(20)

exec :dname:=get_into('smith',:job)

 

三：管理子程序

1.  列出當前子程序

col object_name format a20

SELECT object_name,created,status FROM user_objects

WHERE object_type IN ('PROCEDURE','FUNCTION');

習題：

1.      建立過程UPD_SHIPDATE,根據輸入的訂單號和交付日期，更新ORD表特定訂單的交付日期，然後調用該過程。當建立過程UPD_SHIPDATE時，實現

1.如果交付日期小於預定日期，則顯示自定義錯誤

2.如果訂單不存在，。。。。。

CREATE OR REPLACE PROCEDURE upd_shipdate(

  2  id NUMBER,shipdate DATE)

  3  IS

  4   orddate DATE;

  5  BEGIN

  6   UPDATE ord SET ship_date=shipdate

  7   WHERE ord_id=id RETURNING ord_date INTO orddate;

  8   IF SQL%NOTFOUND THEN

  9    RAISE_APPLICATION_ERROR(-20002,'該訂單不存在');

 10   END IF;

 11   IF shipdate < orddate THEN

 12    ROLLBACK;

 13    RAISE_APPLICATION_ERROR(-20001,'交付日期不能小於預定日期');

 14   END IF;

END;