1. 统计每年入职的员工人数

 1 set SERVEROUTPUT ON;
 2 declare
 3 cursor cemp is select to_char(hiredate,'yyyy') from emp;
 4 phiredate VARCHAR2(4);
 5 count80 number:=0;
 6 count81 number:=0;
 7 count82 number:=0;
 8 count83 number:=0;
 9 begin   
10 open cemp;
11 loop
12 fetch cemp into phiredate;
13 exit when cemp%notfound;
14 if phiredate='1980' then count80:=count80+1;
15 elsif phiredate='1981' then count81:=count81+1;
16 elsif phiredate='1982' then count82:=count82+1;
17 else  count83:=count83+1;
18 end if;
19 end loop;
20 close cemp;
21 dbms_output.put_line('total:'||(count80+count81+count82+count83));
22 end;
23 /