Oracle的PL/SQL编程和游标

PL/SQL的基本构成

数据类型

集合类型

基本控制语句

异常处理

系统异常的几种:

[align=left]cursor_already_open 当游标已经open,执行open,产生此异常.[/align]

[align=left]dup_val_on_index insert操作进,违反了unique约束,产生此异常.[/align]

[align=left]invalid_number [/align]

[align=left]no_ data_found[/align]

[align=left]too_many_rows 多个记录的select into 的语句,产生此异常.[/align]

[align=left]等等...[/align]

[align=left]declare
l_dept departments%rowtype;
begin
l_dept.department_id=100;
l_dept.department_name='dong';
insert into departments(department_id,department_name) [/align]
[align=left] values(l_dept.department_id,l_dept.department_name);
exception
when dup_val_on_index then
dbms_output.put_line('违反unique约束');
when others then
dbms_output.put_line('不明的异常');
end;[/align]

自定义的异常:

create or replace function divide(a int,b int) return int
is
begin
if(b=0) then
raise_application_error('-20001','second parameter not is zero'); --throws exception
end if;
return a/b;
end;
--PL/SQL语言部分
declare
a int:=10;
b int:=0;
c int:=0;
begin
c:=divide(a,b);
exception
when others then
if sqlcode=-20001 then
dbms_output.put_line('myerror');
end if;
end;

delare中产生的异常不会被Exception捕捉到,系统会报错

declare
i number default 'sfd'; --declare声明块中的异常由系统msgbox出来
begin
null;
exception
when others then
dbms_output.put_line('exceptin catch');
end;
显式游标:

--根据输入的部门号查找hr.employees表的记录
declare
cursor emp_cur(deptid in number) is select * from hr.employees where department_id=deptid;
emp_row hr.employees%rowtype;
begin

open emp_cur(30);
loop
fetch emp_cur into emp_row;
exit when emp_cur%notfound;
dbms_output.put_line(emp_row.employee_id||'is'||emp_row.first_name||emp_row.first_name);
end loop;
close emp_cur;

open emp_cur(60);
loop
fetch emp_cur into emp_row;
exit when emp_cur%notfound;
dbms_output.put_line(emp_row.employee_id||'is'||emp_row.first_name||emp_row.first_name);
end loop;
close emp_cur;
end;

declare
cursor cur is select * from scott.emp;
r scott.emp%rowtype;
begin
open cur;
loop
fetch cur into r;
--如果comm列的值为NULL,则输入nodata
if r.comm is null then
dbms_output.put_line('nodata');
else
dbms_output.put_line(r.comm||'');
end if;
exit when cur%notfound;--cur%found,cur%isopen,cur%rowcount
end loop;
close cur;
end;

--循环游标(优点:更为简洁,不用声明变量,也不需要声明游标变量,隐式的打开和关闭游标)


declare


cursor cur is select * from scott.emp;


begin


for emprow in cur --(for emprow : cur)


loop


if emprow.comm is null then


dbms_output.put_line('nodata');


else


dbms_output.put_line(emprow.comm||'');


end if;


end loop;


end;

隐式的游标

begin
update scott.emp set empno=empno ;
if sql%found then
dbms_output.put_line(sql%rowcount);
else
dbms_output.put_line('notfound');
end if;
end
另外一种隐式的游标用FOR LOOP语句（隐式的打开和关闭游标）

begin
for dept in (select * from departments)
loop
dbms_output.put_line(dept.department_id);
dbms_output.put_line(dept.department_name);
end loop;
end;
Ref cursor(变化的游标)

declare
type emp_cursortype is ref cursor return scott.emp%rowtype;
cur emp_cursortype;
emprow scott.emp%rowtype;
begin
open cur for select * from scott.emp;
loop
fetch cur into emprow;
if emprow.comm is null then
dbms_output.put_line('nodata');
else
dbms_output.put_line(emprow.comm||'');
end if;
exit when cur%notfound;
end loop;
close cur;

dbms_output.put_line('查找COMM>100');

open cur for select * from scott.emp where comm>100;
loop
fetch cur into emprow;
if emprow.comm is null then
dbms_output.put_line('nodata');
else
dbms_output.put_line(emprow.comm||'');
end if;
exit when cur%notfound;
end loop;
close cur;
end;
用select 语句为集合变量复值

declare
TYPE namearray IS TABLE OF VARCHAR2(40) INDEX BY binary_integer;
names namearray;
TYPE idarray IS TABLE OF integer INDEX BY binary_integer;
empnos idarray;
BEGIN
--返回多个记录时赋予集合数据
SELECT ename,empno bulk collect INTO names,empnos FROM scott.emp;
FOR i IN names.first..names.last
LOOP
dbms_output.put_line(names(i)|| ' '||empnos(i));
END LOOP;
END;

游标