Oracle之PL/SQL学习笔记

-- 使用匿名过程完成工资修改
SET SERVEROUT ON ;
DECLARE
	l_salary NUMBER(5) ;
	l_empno NUMBER(4) ;	
BEGIN
	l_empno := 7369 ;	-- initialize must be execution section
	SELECT sal INTO l_salary FROM emp WHERE empno=l_empno ;
	IF l_salary > 500 THEN 		
		UPDATE emp SET sal = l_salary+500 WHERE empno=l_empno ;
	END IF;
	EXCEPTION	-- Handle Exception
		WHEN NO_DATA_FOUND THEN
			DBMS_OUTPUT.PUT_LINE('NO DATA FOUND') ;
END ;

-- 创建命名嵌套存储过程完成工资修改
SET SERVEROUT ON ;
CREATE OR REPLACE PROCEDURE change_salary IS
-- DECLARE		-- 命名存储过程不需要DECLARE
	l_salary NUMBER(5) ;
	l_empno NUMBER(4) := 7369 ;	
BEGIN
	-- l_empno := 7369 ;	-- initialize must be execution section
	SELECT sal INTO l_salary FROM emp WHERE empno=l_empno ;
	IF l_salary > 500 THEN 		
		UPDATE emp SET sal = l_salary-500 WHERE empno=l_empno ;
	END IF;
		BEGIN
			DBMS_OUTPUT.PUT_LINE('NESTED SECSION') ;
		END ;
	EXCEPTION	-- Handle Exception
		WHEN NO_DATA_FOUND THEN
			DBMS_OUTPUT.PUT_LINE('NO DATA FOUND') ;
END ;

-- 定义变量
identifier [CONSTANT] datatype [NOT NULL]  [:= | DEFAULT expr];
v_hirdate DATE ;
v_empno emp.empno%TYPE := 7369 ;

DECLARE
	emp_count NUMBER ;
BEGIN
	SELECT COUNT(*) INTO emp_count FROM employees WHERE department_id=&department_id;
	DBMS_OUTPUT.PUT_LINE('count'||':'||emp_count) ;
END ;

-- Returning 子句
DECLARE 
	myname employees.last_name%TYPE ;
	mysal employees.salary%TYPE ;
BEGIN
	FOR rec IN (SELECT * FROM employees) 
	LOOP
		UPDATE employees SET salary = rec.salary/1 WHERE rec.employee_id = employee_id -- 此处不可加分号
		RETURNING last_name,salary INTO myname,mysal ;	-- 将修改后的值放入到变量中
		DBMS_OUTPUT.PUT_LINE('myname:'||myname||',sal:'||mysal) ;
	END LOOP ;
END ;

-- IF Statement
DECLARE
	v_start NUMBER:=1000 ;
BEGIN
	IF v_start>100 THEN
		v_start:=2*v_start ;
	ELSIF v_start>50 THEN
		v_start:=5*v_start ;
	ELSE
		v_start:=0.1*v_start ;
	END IF ;
	DBMS_OUTPUT.PUT_LINE(v_start) ;
END ;

-- CASE Statement(Start with 'CASE' end by 'END')
SET SERVEROUT ON ;
DECLARE 
	-- no NUMBER :=100 ;
	no2 NUMBER:= &i ;
BEGIN
	CASE no2
	WHEN 100 THEN
		DBMS_OUTPUT.PUT_LINE(100) ;
	WHEN 200 THEN
		DBMS_OUTPUT.PUT_LINE(200) ;
	WHEN 300 THEN
		DBMS_OUTPUT.PUT_LINE(300) ;
	ELSE
		DBMS_OUTPUT.PUT_LINE('DEFAULT') ;
	END CASE ;
END ;

-- Select语句中使用Case块
SELECT empno,CASE empno 
		WHEN 7369 THEN 'SMITH'
		WHEN 7499 THEN 'ALLEN'
		ELSE 'AKWOLF'
		END FROM emp ;

SELECT COUNT(CASE WHEN sal<1000 THEN 1 ELSE NULL END) count1,
	COUNT(CASE WHEN sal>=1000 AND sal<2000 THEN 1 ELSE NULL END) count2
	from emp ;

-- Basic Loop
DECLARE
	v_orderid NUMBER:=1014 ;
	v_counter NUMBER:=1 ;
BEGIN
	LOOP
		INSERT INTO item VALUES(v_orderid,v_counter) ;
		v_counter := v_counter+1 ;
		EXIT WHEN v_counter>10 ;
	END LOOP ;
END ;

-- For Loop
DECLARE
	v_orderid NUMBER :=199 ;
BEGIN
	FOR i IN 1..20 LOOP
		INSERT INTO item VALUES(v_orderid,i) ;
	END LOOP ;
END;

-- While Loop
DECLARE
	v_qty NUMBER :=1 ;
	v_total NUMBER :=0 ;
BEGIN
	WHILE v_total<	&input LOOP
		v_qty :=v_qty+1 ;
		v_total := v_qty*&price ;
		DBMS_OUTPUT.PUT_LINE(v_total) ;
	END LOOP ;
END ;

-- CURSOR游标
DECLARE
	CURSOR emp_cur IS SELECT * FROM emp ;
BEGIN
	FOR emp_rec IN emp_cur LOOP
		DBMS_OUTPUT.PUT_LINE('empno: '||emp_rec.empno||' ,ename: '||emp_rec.ename) ;
	IF SQL%FOUND THEN
		DBMS_OUTPUT.PUT_LINE('FOUND -->'||emp_rec.empno) ;
	ELSIF SQL%NOTFOUND THEN
		DBMS_OUTPUT.PUT_LINE('NOTFOUND -->') ;
	ELSIF NOT SQL%ISOPEN THEN
		DBMS_OUTPUT.PUT_LINE('NOT OPEN -->') ;	
	ELSE
		DBMS_OUTPUT.PUT_LINE('THIS SESCTION HAS EXECTION'||SQL%ROWCOUNT) ;
	END IF ;
	END LOOP ;
END ;