PLSQL_结构、存储过程、函数

/**************************************002 PLSQL结构、存储过程、函数 *****************************************/
/**
[DECLARE declarations]
BEGIN
executable statements
[EXCEPTION handlers]
END;
*/
DECLARE
v_ename emp.ename%TYPE;
BEGIN
SELECT ename INTO v_ename FROM emp WHERE empno = &empno;
dbms_output.put_line('员工姓名:' || v_ename);
EXCEPTION
WHEN NO_DATA_FOUND
THEN dbms_output.put_line('查无此人!');
END;

/**
条件判断
IF boolean THEN executable END IF;
IF boolean THEN executable ELSE executable END IF;
IF boolean THEN executable ELSIF boolean THEN executable ELSE executable END IF;
*/

/**
循环 (LOOP WHILE FOR)
*/
-- LOOP
DECLARE
j NUMBER := 0;
BEGIN
j := 1;
LOOP
dbms_output.put_line(j);
EXIT WHEN j >= 7;
j := j + 1;
END LOOP;
END;

-- WHILE
DECLARE
j NUMBER := 0;
BEGIN
j := 1;
WHILE j <= 8
LOOP
dbms_output.put_line(j || '---');
j := j+1;
END LOOP;
END;

-- FOR
DECLARE
j NUMBER := 0;
BEGIN
FOR j IN 1..8
LOOP
dbms_output.put_line(j || '---');
END LOOP;
END;

/**
存储过程.PROCEDURE
参数形式三种 (in, outm in out)
*/

-- 001 in example
CREATE OR REPLACE PROCEDURE PROC1(i IN NUMBER)
AS
a VARCHAR2(50);
BEGIN
a := '';
FOR j IN 1..i
LOOP
a := a || '*';
dbms_output.put_line(a);
END LOOP;
END;

-- 两种方式调用存储过程 1 通过exec执行 2 通过块执行
-- exec PROC1(4);
BEGIN
PROC1(7);
END;

-- 002 out example

CREATE OR REPLACE PROCEDURE PROC2(i OUT NUMBER)
AS
BEGIN
i := 100;
dbms_output.put_line(i);
END;

DECLARE
k NUMBER;
BEGIN
PROC2(K);
dbms_output.put_line(k);
END;

-- 003 in out example

CREATE OR REPLACE PROCEDURE PROC3(p1 IN OUT NUMBER , p2 IN OUT NUMBER)
AS
v_temp NUMBER;
BEGIN
v_temp := p1;
p1 := p2;
p2 := v_temp;
END;

DECLARE
num1 NUMBER := 10;
num2 NUMBER := 20;
BEGIN
PROC3(num1, num2);
dbms_output.put_line(num1);
dbms_output.put_line(num2);
END;

/**
函数：（函数是可以返回值的命名的PL/SQL 子程序）
CREATE [OR REPLACE] FUNCTION <FUNCTION NAME> [(PARAM...)]
RETURN <DATATYPE> IS|AS
[LOCAL DECLARATIONS]
BEGIN
EXECUTABLE STATEMENTS;
RETURN RESULT;
EXCEPTION
EXCEPTION HANDLERS;
END;
*/

-- 001 要求：创建一个函数,可以接受用户输入的学号，得到该学生的名次，输出名次。
/**
-- 实验准备
CREATE TABLE STUDENT (STU_NO NUMBER(3), NAME VARCHAR2(10), SCORE NUMBER(3));
INSERT INTO STUDENT VALUES (1 , '小小', 99);
INSERT INTO STUDENT VALUES (2 , '小G', 80);
INSERT INTO STUDENT VALUES (3 , '诺诺', 98);
INSERT INTO STUDENT VALUES (4 , '小北', 79);
COMMIT;
SELECT * FROM STUDENT;
*/

CREATE OR REPLACE FUNCTION FUNC1(SNO INT) RETURN INT
AS
v_score NUMBER;
v_mingci NUMBER;
BEGIN
SELECT SCORE INTO v_score FROM STUDENT WHERE STU_NO = SNO;
SELECT COUNT(*) INTO v_mingci FROM STUDENT WHERE SCORE > v_score;
v_mingci := v_mingci + 1;
RETURN v_mingci;
END;

SELECT FUNC1(3) FROM DUAL;