pl/sql 实例解析 01

1. 合并 firstname, lastname.

declare
    v_first_name    varchar2(255);
    v_last_name        varchar2(255);
begin
    select first_name, last_name
      into v_first_name, v_last_name
      from student
     where student_id = 777;

    dbms_output.put_line('Student Name: ' || v_first_name || ' ' || v_last_name);
exception
    when no_data_found then
        dbms_output.put_line('There is no data');
end;
/
show errors;

2. 使用替代变量, 交互内容, 个人感觉替代变量并不常用, 真正生产情况时, 那有那么多人来输入替代变量的值啊.

/*
 * 测试替代变量
 * sv_student_id, sv 个人理解是 system value的意思
*/

declare
	v_student_id number := &sv_student_id;
	v_first_name varchar2(255);
	v_last_name varchar2(255);
begin
	select first_name, last_name
	  into v_first_name, v_last_name
	  from student
	 where student_id = &sv_student_id;
	
	dbms_output.put_line('Student Name: ' || v_first_name || '' || v_last_name);
exception
	when no_data_found then
		dbms_output.put_line('There is no student');
end;
/
show errors;

注意: 运行以上例子2 时, 系统会给出提示, 让你输入 student_id 的值, 然后会显示 old_value, new_value