pl sql练习（1）

1. 编写函数接受参数并返回字符串：Hello $var.然后赋值给绑定变量并打印；

 create or replace function hello_function
 ( pv_whom varchar2 ) return varchar2 is
 begin
 return 'Hello '||pv_whom||'.';
 end;
 /

 SQL> variable result varchar2(20);
 SQL> call hello_function('Sam') into :result;

 Call completed.

 SQL> print :result

　　2.获取系统精确时间和精确到天的时间

 declare
   lv_date_1 date :=sysdate;
   lv_date_2 date :=lv_date_1;
 begin
   dbms_output.put_line('lv_date_1: '||to_char(lv_date_1,'dd-mon-yy hh24:mi:ss'));
   dbms_output.put_line('lv_date_2: '||to_char(trunc(lv_date_2),'dd-mon-yy hh24:mi:ss'));
 end;
 /

 SQL>
 lv_date_1: 22-8鏈-13 16:33:18
 lv_date_2: 22-8鏈-13 00:00:00

　　3.利用timestamp求出时间间隔

 declare
 lv_interval interval day(9) to second;
 lv_end_day date :=sysdate;
 lv_start_day date := '28-apr-2012';
 begin
   lv_interval :=to_timestamp(lv_end_day) -to_timestamp(lv_start_day);
   dbms_output.put_line(lv_interval);
 end;
 /

 SQL>
 +000000481 18:29:37.000000

　　4.编写一个静态游标

 declare
   cursor c is
   select * from scott.dept;
 begin
   for i in c loop
   dbms_output.put_line(i.loc);
   end loop;
 end;
 /

 SQL>
 NEW YORK
 DALLAS
 CHICAGO
 BOSTON

 PL/SQL procedure successfully completed.

　　5.编写一个动态游标

 declare
      lv_search_sal pls_integer;
      cursor c (cv_search pls_integer) is
      select * from scott.emp where sal>cv_search;
      begin
      for i in c (&input) loop
      dbms_output.put_line(to_char(i.empno)||' '||i.ename||' '||i.job||' '||to_char(i.sal));
      end loop;
    end;
 /

 SQL> @afiedt.buf
 Enter value for input: 990
 old   6:      for i in c (&input) loop
 new   6:      for i in c (990) loop
 7499 ALLEN SALESMAN 1600
 7521 WARD SALESMAN 1250
 7566 JONES MANAGER 2975
 7654 MARTIN SALESMAN 1250
 7698 BLAKE MANAGER 2850
 7782 CLARK MANAGER 2450
 7788 SCOTT ANALYST 3000
 7839 KING PRESIDENT 5000
 7844 TURNER SALESMAN 1500
 7876 ADAMS CLERK 1100
 7902 FORD ANALYST 3000
 7934 MILLER CLERK 1300

　　6.利用游标查找符合要求的行然后更改每一行

 declare
   cursor c is
     select * from scott.emp where sal<990 for update;
 begin
   for i in c loop
     update scott.emp  set sal=sal*1.1
     where current of c;
   end loop;
 end;
 /

　　7.显式游标的批量处理数据，建议取游标集合中的250~300条数据一次性处理；

 declare
   type people_record is record
     (ename varchar2(30),sal pls_integer);
   type people_collection is table of people_record;
   lv_people_collection people_collection;
   cursor c is
     select ename,sal from scott.emp;
 begin
   open c;
   loop
     fetch c bulk collect into lv_people_collection limit 5;
     exit when lv_people_collection.count=0;
     for i in 1..lv_people_collection.count loop
       dbms_output.put_line(lv_people_collection(i).ename||' '||to_char(lv_people_collection(i).sal));
     end loop;
     dbms_output.put_line(to_char(c%rowcount));
   end loop;
   close c;
 end;
 /
 ~

 SQL> @a.sql;
 SMITH 800
 ALLEN 1600
 WARD 1250
 JONES 2975
 MARTIN 1250
 5
 BLAKE 2850
 CLARK 2450
 SCOTT 3000
 KING 5000
 TURNER 1500
 10
 ADAMS 1100
 JAMES 950
 FORD 3000
 MILLER 1300
 14

 PL/SQL procedure successfully completed.