PL/SQL 语言 一

Declare
 a Varchar2(20);
 b Number(10);
 c Number(10);
 
 m Number(5);
 sname Varchar2(20);
 
 nozero Exception;
 
Begin
  a := '小明';
  Dbms_Output.Put_Line(a);

  b := 3;
  c := 0;
  
  
 /* 循环 */ 
/* 
    m :=50;

    Loop 
    Exit When m<0;
    dbms_output.put_line(m);
    m := m-1;
    End Loop;  */
    
/*    While m>0
    Loop
      dbms_output.put_line(m);
      m := m-1;
    End Loop; */
    
/*    For n In 1..5 
    Loop
      dbms_output.put_line(n);
    End Loop; */
    
/*    Select s.Name Into Sname From z_Student s Where s.Id = m;
    Dbms_Output.Put_Line('查询结果:' || Sname);
  Exception 
      When No_Data_Found Then
       Dbms_Output.Put_Line('没有查询到数据'); */
   
  If b=0 Or c=0 Then
    Raise nozero;
  End If;
   
  If b > c Then
    Dbms_Output.Put_Line('b大于c');
  Elsif b < c Then
    Dbms_Output.Put_Line('b小于c');
  Else
    Dbms_Output.Put_Line('b等于c');
  End If;
  
  
  Exception
  When nozero Then 
    dbms_output.put_line('b和c都不能为0！');  
  When Others Then
    dbms_output.put_line('其他异常！');
  
End;