学习笔记：19pl/sql函数

19-1:建立无参数的函数
	CREATE OR REPLACE FUNCTION cur_datetime
	RETURN VARCHAR2
	IS
	BEGIN
	  RETURN TO_CHAR(sysdate,
	    'YYYY"年"MM"月"DD"日"HH24"时"MI"分"SS"秒"');
	END;
	/
19-2:建立带有输入参数的函数
	CREATE OR REPLACE FUNCTION get_sal(name 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;
	END;
	/
19-3:建立带有输出参数的函数
	CREATE OR REPLACE FUNCTION get_info
	(eno NUMBER,title OUT VARCHAR2) RETURN VARCHAR2
	AS
	  name emp.ename%TYPE;
	BEGIN
	  SELECT ename,job INTO name,title FROM emp
	  WHERE empno=eno;
	  RETURN name;
	END;
	/
19-4:建立带有输入输出参数的函数
	CREATE OR REPLACE FUNCTION get_upd_info
	(eno NUMBER,sal_chg IN OUT NUMBER) RETURN VARCHAR2
	AS
	  name emp.ename%TYPE;
	BEGIN
	  UPDATE emp SET sal=sal+sal_chg WHERE empno=eno
	    RETURNING ename,sal INTO name,sal_chg;
	  RETURN name;
	END;
	/

19-5:建立结果缓存函数
CREATE OR REPLACE FUNCTION get_name(no VARCHAR2)
RETURN NUMBER RESULT_CACHE RELIES_ON(emp)
AS
  v_name emp.ename%TYPE;
BEGIN
  SELECT ename INTO v_name FROM emp WHERE empno=no;
  RETURN v_name;
END;
/

19-6:调用无参数的函数
	BEGIN
	  dbms_output.put_line(cur_datetime);
	END;
	/
19-7:调用带有输入参数的函数
	BEGIN
	  dbms_output.put_line('工资:'||get_sal('&name'));
	END;
	/
19-8:调用带有输出参数的函数
	DECLARE
	  v_name emp.ename%TYPE;
	  v_job emp.job%TYPE;
	BEGIN
	  v_name:=get_info(&eno,v_job);
	  dbms_output.put_line('姓名:'||v_name||',岗位:'||v_job);
	END;
	/
19-9:调用带有输入输出参数的函数
	DECLARE
	  v_empno emp.empno%TYPE;
	  v_name emp.ename%TYPE;
	  v_salchg emp.sal%TYPE;
	BEGIN
	  v_empno:=&eno;
	  v_salchg:=&incre;
	  v_name:=get_upd_info(v_empno,v_salchg);
	  dbms_output.put_line('姓名:'||v_name||',新工资:'||v_salchg);
	END;
	/
19-10:使用位置传递为参数传递变量和数据
	SELECT get_sal('&name') 工资 FROM dual;
19-11:使用名称传递为参数传递变量和数据
	VAR salary NUMBER
	EXEC :salary:=get_sal(name=>'&name')
19-12:使用组合传递为参数传递变量和数据
	VAR name VARCHAR2(10)
	VAR sal_chg NUMBER
	EXEC :sal_chg:=200
	EXEC :name:=get_upd_info(&eno,:sal_chg)
	PRINT name sal_chg
19-13:在sql语句中调用pl/sql函数
  	SELECT get_sal(name=>'scott') salary FROM dual;
19-14:使用异常处理
	CREATE OR REPLACE FUNCTION get_sal(name 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,'该雇员不存在');
	END;
	/
19-15:使用纪录类型作为返回类型
	CREATE OR REPLACE FUNCTION get_info
	(eno NUMBER) RETURN emp%ROWTYPE
	IS
	  emp_record emp%ROWTYPE;
	BEGIN
	  SELECT * INTO emp_record FROM emp WHERE empno=eno;
	  RETURN emp_record;
	EXCEPTION
	  WHEN NO_DATA_FOUND THEN
	    RAISE_APPLICATION_ERROR(-20000,'该雇员不存在');
	END;
	/
	DECLARE
	  emp_record emp%ROWTYPE;
	BEGIN
	  emp_record:=get_info(&eno);
	  dbms_output.put_line('姓名:'||emp_record.ename||',部门号:'||emp_record.deptno);
	END;
	/
19-16:使用集合类型作为返回类型
	CREATE OR REPLACE TYPE ename_table_type IS TABLE OF VARCHAR2(10);
	/
	CREATE OR REPLACE FUNCTION get_name
	(dno NUMBER) RETURN ename_table_type IS
	  ename_table ename_table_type;
	BEGIN
	  SELECT ename BULK COLLECT INTO ename_table FROM emp WHERE deptno=dno;
	  RETURN ename_table;
	EXCEPTION
	  WHEN NO_DATA_FOUND THEN
	     RAISE_APPLICATION_ERROR(-20099,'该部门不存在');
	END;
	/
	DECLARE
	  ename_table ename_table_type;
	BEGIN
	  ename_table:=get_name(&dno);
	  FOR i IN 1..ename_table.COUNT LOOP
	    dbms_output.put_line('姓名：'||ename_table(i));
	  END LOOP;
	END;
	/
19-17:删除函数
	DROP FUNCTION get_name;
19-18:显示编译错误
	SHOW ERRORS
19-19:确定函数状态
	SELECT object_name FROM user_objects WHERE status='INVALID' AND object_type='FUNCTION';
19-20:编译函数
	ALTER FUNCTION get_info COMPILE;
19-21:查看函数代码
	SELECT text FROM user_source WHERE name='GET_INFO';