1.选择语句

1.1 IF...THEN...END IF语句

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DECLARE MY_AGE INT;
IF MY_AGE IS NULL THEN
     DBMS_OUTPUT.put_line('AGE IS NULL');
END IF;

　　

1.2 IF...THEN ELSIF THEN....ELSE THEN... ENDIF语句，这里需要注意的是ELSIF这个，JAVA里面的写法就是 else if  这里是ELSIF，IF前面不能有空格。

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IF AGE <= 6 AND AGE > 0 THEN
    DBMS_OUTPUT.put_line('CHILD');
  ELSIF AGE <= 17 AND AGE > 6 THEN
    DBMS_OUTPUT.put_line('TEENAGER');
  ELSIF AGE <= 40 AND AGE > 17 THEN
    DBMS_OUTPUT.put_line('YOUTH');
  ELSIF AGE <= 65 AND AGE > 40 THEN
    DBMS_OUTPUT.put_line('Middle-aged');
  ELSIF AGE > 65 AND AGE<= 150 THEN
    DBMS_OUTPUT.put_line('OLDER');
  ELSE
    DBMS_OUTPUT.put_line('YOU AGE IS OUT OF SPACE');
  END IF;

1.3.CASE 语句

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CASE AGE
    WHEN 1 THEN  DBMS_OUTPUT.put_line('BABY');
    WHEN 15 THEN  DBMS_OUTPUT.put_line('TEENAGER');
    WHEN 25 THEN  DBMS_OUTPUT.put_line('ADULT');
    ELSE DBMS_OUTPUT.put_line('OLDER');
   END CASE;
   END;

2.循环语句

2.1 LOOP 语句

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DECLARE RESULT NUMBER:=0;
NUM1 NUMBER:=1;
NUM2 NUMBER:=100;
 
 
 LOOP
    RESULT:=RESULT+NUM1;
    NUM1:=NUM1+1;
    EXIT WHEN NUM1>NUM2;
  END LOOP;
   
  DBMS_OUTPUT.put_line('LOOP RESUT IS:'||RESULT);

2.2 WHILE语句

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WHILE NUM1<=NUM2 LOOP
   RESULT:=RESULT+NUM1;
   NUM1:=NUM1+1;
 END LOOP;
 DBMS_OUTPUT.put_line(RESULT);

2.3 FOR语句

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FOR J IN REVERSE NUM1..NUM2 LOOP
    RESULT:=RESULT+J;
    DBMS_OUTPUT.put_line(J);
  END LOOP;
  DBMS_OUTPUT.put_line(RESULT);