Oracle——循环（LOOP、WHILE、FOR）

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循环控制用于重复执行一系列语句

循环控制语句包括：

LOOP、EXIT 和 EXIT WHEN、END LOOP

循环控制的三种类型：

LOOP   -   基本循环

WHILE  -  根据条件循环

FOR  - 固定次数的循环

create table T_TEST
(
  id number(5),
  num number(10)
);

LOOP

语法

LOOP

   sequence_of_statements

END LOOP;

示例

DECLARE
v_count NUMBER(5):=1;
v_num NUMBER(10):=100;
BEGIN
LOOP
	INSERT INTO T_TEST(T_TEST."id",T_TEST."num")
	VALUES(v_count,v_num);
	v_count:= v_count + 2;
	v_num:= v_num + 10;
	IF v_count > 10 THEN
		EXIT; 
	END IF; 
END LOOP;
dbms_output.put_line('成功');
END;

WHILE

语法

WHILE condition LOOP 
   sequence_of_statements
END LOOP;

示例

DECLARE
v_count NUMBER(5):=11;
v_num NUMBER(10):=200;
BEGIN
while v_count < 20
LOOP
	INSERT INTO T_TEST(T_TEST."id",T_TEST."num")
	VALUES(v_count,v_num);
	v_count:= v_count + 3;
	v_num:= v_num + 10;
END LOOP;
END;

FOR

语法

FOR  counter  IN [REVERSE] value1..value2   LOOP 
  sequence_of_statements
END LOOP;

示例

DECLARE
v_count NUMBER(5):=20;
v_num NUMBER(10):=300;
BEGIN
FOR v_count IN 20..30 LOOP
	INSERT INTO T_TEST(T_TEST."id",T_TEST."num")
	VALUES(v_count,v_num);
	v_num:= v_num + 10;
END LOOP;
END;