PL/SQL 控制语句

1. 条件语句：
   1. if...then...else语句：

      declare
        l_num number := #
        begin
            if  l_num = 1 then
              dbms_output.put_line(1);
            elsif l_num = 2 then
              dbms_output.put_line(2);
            else
              dbms_output.put_line('other');
            end if;
        end;

       
   2. case语句：

      declare
        l_num number := #
        begin
            case l_num
              when 1 then dbms_output.put_line('1');
              when 2 then dbms_output.put_line('2');
              when 3 then dbms_output.put_line('3');
              when 4 then dbms_output.put_line('4');
              else dbms_output.put_line('more');
             end case;
        end;

2. 循环语句：
   1. 无限制循环：

        /**
         * loop 循环
         */
        declare
        r_number number :=0;
        begin
          loop
          -- 使用if和exit命令退出
            if r_number > 4 then exit;
            end if;
            dbms_output.put_line('number:'||r_number);
            r_number := r_number+1;
          end loop;
        end;
       
        declare
        r_number number :=0;
        begin
          loop
          -- 使用exit when命令退出
            exit when r_number >4;
            dbms_output.put_line('number:'||r_number);
            r_number := r_number+1;
          end loop;
        end;

       
   2. While循环：

      /*
         * while 循环
         */
        declare
        r_number number :=0;
        begin
          while r_number <5 loop
            dbms_output.put_line(r_number);
            r_number := r_number + 1;
          end loop;
          dbms_output.put_line(r_number);
        end;

       
   3. for 循环：

        /*
         * for 循环
         */
        declare
        r_number number :=5;
        begin
          for var_index in 1..r_number loop
            dbms_output.put_line(var_index);
          end loop;
        end;
        
        declare
        cursor my_cursor is select * from emp;         
        begin
          for cursor_record in my_cursor loop
            dbms_output.put_line(cursor_record.ename);
          end loop;
        end;