例外

--no_data_found
declare
pename emp.ename%type;
begin
select ename into pename from emp where empno = 1234;
exception
when no_data_found then
dbms_output.put_line('没有找到该员工');
when others then
dbms_output.put_line('Other');
end;

--too_many_rows

declare
pename emp.ename%type;
begin
select ename into pename from emp where deptno = 10;
exception
when too_many_rows then
dbms_output.put_line('select into 匹配多行');
when others then
dbms_output.put_line('Other');
end;

--zero_divide
declare
pnum number;
begin
pnum := 1 / 0;
exception
when zero_divide then--then相当于一个大括号，可以有多条语句
dbms_output.put_line('1.0不能做被除数');
dbms_output.put_line('2.0不能做被除数');
when others then
dbms_output.put_line('其他');
end;

--value_error
declare
pnum number;
begin
pnum := 'abc';
exception
when value_error then
dbms_output.put_line('类型错误');
when others then
dbms_output.put_line('其他');
end;

--自定义例外：查询50号部门的员工姓名
declare
cursor cemp is
select ename from emp where deptno = 50;
pename emp.ename%type;
no_emp_found exception; --自定义例外
begin
open cemp;
fetch cemp
into pename;
if cemp%notfound then
raise no_emp_found;
end if;
exception
when no_emp_found then
dbms_output.put_line('没有找到员工');
when others then
dbms_output.put_line('Others');
close cemp;
end;