ORACLE PL/SQL 结构控制

结构控制
使用IF语句按条件判断,控制PL/SQL执行流程:
if-then-end if
if-then-else-end if
if-then-elsif-then-else-end if

set serveroutput on
declare
v_hire_date date := to_date('1995-01-15','yyyy-mm-dd');
v_five_years boolean;
begin
if months_between(sysdate,v_hire_date)/12 > 5 then
v_five_years := true;
dbms_output.put_line('true');
else
v_five_years := false;
dbms_output.put_line('false');
end if;
end;
/

使用CASE表达式:
set serveroutput on
define p_grade='a'
declare
v_grade char(1) := upper('&p_grade');
v_appraisal varchar2(20);
begin
v_appraisal :=
case v_grade
when 'A' then 'excellent'
when 'B' then 'very good'
when 'C' then 'good'
else 'no such grade!'
end;
dbms_output.put_line ('grade: '|| v_grade || ' appraisal ' || v_appraisal);
end;
/

DECLARE
v_grade CHAR(1) := UPPER('&p_grade');
v_appraisal VARCHAR2(20);
BEGIN
v_appraisal :=
CASE --省略
WHEN v_grade='A' THEN 'Excellent'
WHEN v_grade='B' THEN 'Very Good'
WHEN v_grade='C' THEN 'Good'
ELSE 'No such grade'
END;
DBMS_OUTPUT.PUT_LINE ('Grade: '|| v_grade || ' Appraisal ' || v_appraisal);
END;
/

循环遍历控制:
1.基本LOOP循环:
set serveroutput on
declare
i integer :=1;
begin
loop
dbms_output.put_line(i);
i := i+1;
exit when i>10;
end loop;
end;
/

while循环:
declare
i integer :=1;
begin
while i<=10 loop
dbms_output.put_line(i);
i := i+1;
end loop;
end;
/

数字for循环:
begin
for i in 1..10 loop
dbms_output.put_line(i);
end loop;
end;
/

begin
for i in reverse 1..10 loop
dbms_output.put_line(i);
end loop;
end;
/

实现双重循环
外循环和内循环都执行5次.
内外计数器变量名相同:i
显示内循环的计数器和外循环的计数器的乘积
当乘积超过15时候,退出
declare
v_plus number(10);
begin
<<outer_loop>>
for i in 1..5 loop
<<inner_loop>>
for i in 1..5 loop
v_plus:=i*outer_loop.i;
exit when v_plus>15;
dbms_output.put_line(v_plus);
end loop inner_loop;
--dbms_output.put_line('Loop count : '||i);
end loop outer_loop;
end;
/

标号和goto:
declare
v_counter number := 1;
begin
loop
dbms_output.put_line('in loop V_counter current value:'||V_counter);
v_counter := v_counter + 1;
if v_counter > 10 then
goto l_ENDofLOOP;
end if;
end loop;
<<l_ENDofLOOP>>
dbms_output.put_line('end loop V_counter current value:'||V_counter);
end;
/

打印乘法口诀表:
declare
i int := 1;
j int := 1;
begin
for i in 1 .. 9 loop
for j in 1 .. i loop
dbms_output.put(j || ' * '|| i || ' = ' || i*j || ' ');
end loop;
dbms_output.put_line(' ');
end loop;
end;
/

写一个PL/SQL块
向dept表中循环插入5条记录
每一条记录的deptno 值比表中最大的deptno 值增加1
dname分别为"Test1" "Test2"..."Test5"
loc列的值都为空。

declare
v_deptno scott.dept.deptno%type;
v_loop number(1):=1;
begin
for i in 1..5 loop
select MAX(deptno) into v_deptno from dept;
insert into dept(deptno,dname)
values ((v_deptno+1),('Test'||to_char(i)));
-- commit;
end loop;
end;
/

事务处理控制语句(COMMIT 和 ROLLBACK):
CREATE TABLE T1(ID INT);
(*批量提交，减少log file sync提高效率!)
DECLARE
V_NUM NUMBER;
BEGIN
FOR V_LOOPCOUNTER IN 1..500 LOOP
INSERT INTO T1 VALUES (V_LOOPCOUNTER);
V_NUM := V_NUM + 1;
IF V_NUM = 50 THEN
COMMIT;
V_NUM := 0;
END IF;
END LOOP;
END;
/

Plsql表+record+循环打印结果集(dept表的所有行所有列)
declare
TYPE CharacterTab IS TABLE OF dept%rowtype
index by binary_integer;
v_Character CharacterTab;
v_max number;
v_deptno number;
begin
select count(*) into v_max from dept;
for i in 1..v_max loop
select deptno,dname,loc
into v_Character(i)
from
(select rownum row_id,d.* from dept d)
where row_id=i;
dbms_output.put_line(v_Character(i).deptno||' '||v_Character(i).dname||' '||v_Character(i).loc);
end loop;
end;
/
练习
1. 循环打印 1 --> 10 不包括6和8！

2. 使用pl/sql查询雇员工资等级，打印结果！

3. 使用PL/SQL从emp表取出数据插入bonus表

4. 如果雇员的奖金小于100，把他的奖金增加工资的10%

5. 使用pl/sql表变量保存dept表所有数据，并打印