declare V_name emp.ename%TYPE :='SMITH';--定义成emp.ename类型,其初始化值必须在ename中存在 V_job  varchar (20)  :='salesman'; V_sal  number ; rec emp%rowtype;begin  select * into rec from emp where ename = V_name; DBMS_OUTPUT.PUT_LINE('姓名:'||rec.ename||'工资:'||rec.sal||'工作时间:'||rec.hiredate);   select ename into V_name from emp where ename = 'WARD'; --dbms_output.put_line('姓名:'||V_name);  if V_name= 'WARD' then   DBMS_output.put_line('姓名:'||V_name||rec.sal);      end if; if V_name='JONES' then     DBMS_output.put_line('Jones今天来上班了');  else      DBMS_output.put_line('Jones今天玩的真happy');    end if;  if V_name = 'SCOTT' then DBMS_output.put_line('scott今天来上班了');   elsif  V_name = '十大队'  then DBMS_output.put_line('ward今天来上班了'); else        DBMS_output.put_line('今天没人上班,公司空空如也');    end if;  end;--case的 应用练习  V_APPraisal :=的值为 case语句的返回值 declare         V_grade char(1) :='A';        V_APPraisal varchar2(20); begin   V_APPraisal :=  --case内部不用加 ; 只有在结束时再加.    case V_grade     when 'A'  then 'excellent'     when 'B'  then 'vary good'     when 'C' then  'GOOG'     else  'no such grade'   end;   DBMS_OUTPUT.PUT_LINE('Grade:'||V_grade||'    Appraisal: '|| V_APPraisal); end;  CREATE TABLE OWER (TIME date ,NAME varchar(10), NUM number(2));declare       INT number(2):= 1;BEGIN   LOOP           INT := INT +1;       INSERT INTO OWER (TIME,NAME,NUM)       VALUES (SYSDATE ,'HHH',5);       dbms_output.put_line ('想看看你打印了'||to_char(int)||'次');       dbms_output.put_line (int);       exit when int=8;    --循环内容包含此处的值   end loop;end;  select * from ower; declare     int number := 1; begin   while int<10 loop --等于10 的时候退出      dbms_output.put_line ('想看看你打印了'||to_char(int)||'次');      int:= int+1;      end loop; end;  create table temp_table(num_col number(10))  ;      DECLARE        V_counter NUMBER := 10;BEGIN   INSERT INTO temp_table(num_col) VALUES (v_counter );   FOR v_counter IN 20 .. 25 LOOP  -- 打印出20 ,到25 行的内容.      INSERT INTO temp_table (num_col ) VALUES ( v_counter );   END LOOP;   INSERT INTO temp_table(num_col) VALUES (v_counter );   FOR v_counter IN REVERSE 20 .. 25 LOOP      INSERT INTO temp_table (num_col ) VALUES ( v_counter );   END LOOP;END ;