关于Oracle过程，函数的经典例子及解析
以下皆为自己的学习感受，存档加分享。存档在先，分享在后，若有不妥之处，并无误人子弟之意，请各位AC之间的大牛不吝指教，小生在此鞠躬谢过。
一，Oracle中的过程，函数
对于oracle中的过程和函数，个人觉得可以化为一类，因为它们在写法上并没有什么的不同。公式无非就是
create or replace Package_name(paramater1 in type,paramater2 in type,out_message out type)
is
locate_paramater1 type;
locate_paramater2 type;
begin
begin
select sth into locate_paramater1 from table_name where 。。。。
exception
when no_data_found then
locate_paramater1:=' ';
out_message:='Some Information to user to look';
end
begin
select sth into locate_paramater2 from table_name where 。。。。
exception
when no_data_found then
locate_paramater2:=' ';
out_message:='Some Information to user to look';
end
end
总而言之，言而总之：包声明，私有数据神马的在紧跟is之后。接着就是一串的begin......exception....end;
函数
create or replace function_name(paramater1 in type,paramater2 in type)
return return_type;
is
locate_paramater1 type;
locate_paramater2 type;
out_message return_type;
begin
begin
select sth into locate_paramater1 from table_name where 。。。。
exception
when no_data_found then
locate_paramater1:=' ';
out_message:='Some Information to user to look';
return out_message;
when others then
out_message:='Error';
return out_message;
end
begin
select sth into locate_paramater2 from table_name where 。。。。
exception
when no_data_found then
locate_paramater2:=' ';
out_message:='Some Information to user to look';
return out_message;
end
end
下面奉上
/* 练习一：
函数：
作一函数，完成下面的功能：
输入姓名，课程名，成绩
该过程完成对SC表的插入或修改操作，
若插入成功，返回成功信息，
若该选课信息已经存在，则修改其成绩为输入的成绩，
若遇系统错误，返回错误信息*/
/*
过程：
建立过程，当传入学号和选课门数，首先判断SC_Number表是否存在
，若不存在则创建该表格（包括学号和选修门数两列），
将传入值插入或修改到SC_Number表中（该生不存在则插入，若存在则修改其选课门数）*/
create or replace procedure inOrUp_Sc_Number(ip_sno in number,ip_courseCount in number)
is
tempt_count number(4);
e_sc_number number(4);
begin
begin
--tab 是一个系统表，存储当前用户下所拥有的表信息
select 1 into e_sc_number from tab where tname='SC_Number';
exception
when no_data_found then
--注意对私有数据的赋值方式!!!!
e_sc_number:=0;
when others then
dbms_output.put_line(sqlerrm);
return;
end;
--endOfBegin
if e_sc_number=0 then
--这个是动态sql,因为在执行这句话之前不知道是否要执行，所以要用动态的
--动态sql的语法：execute immediate 'sql statement'
execute immediate
'create table SC_Number(sno number(5) primary key,cnum number(3) )';
execute immediate
'insert into SC_Number select sno,count(*) from sc group by sno';
commit;
end if;
begin
--这个也是动态sql
--需要注意的是给动态sql，动态的赋值，=：number useing paramater
execute immediate
'select 1 from SC_Number where sno=:1' into tempt_count using trim(ip_sno);
exception
when no_data_found then
tempt_count:=0;
when others then
dbms_output.put_line(sqlerrm);
return;
end;
--endOfBegin
if tempt_count=1 then
begin
execute immediate
--这个还是动态sql
--需要注意的是给动态sql，动态的赋值，=：number useing paramater
'update SC_Number set cnum=:1 where sno=:2'using ip_courseCount,trim(ip_sno);
commit;
exception
when others then
dbms_output.put_line(sqlerrm);
return;
end;
end if;
--endOfIf
if tempt_count=0 then
begin
execute immediate
--为神马这么多动态sql
'insert into SC_Number values(:1,:2)'using ip_sno,ip_courseCount;
commit;
exception
when others then
dbms_output.put_line(sqlerrm);
return;
end;
end if;
--endOfIf
end;
create or replace function func_InsetOrUpdateSc(ip_sname in varchar2,ip_cname in varchar2,ip_grade in varchar2)
--这个是函数的返回类型
return varchar2
is
student_num student.sno%type;
course_num course.cno%type;
out_messsage varchar2(30);--注意私有数据声明时要标注大小
tempt_count number(4);
begin
begin
select sno into student_num from student where student.snmae=ip_sname;
exception
when no_data_found then
student_num:='';
out_messsage:='No such a Student';
return out_messsage;
when others then
out_messsage:='Error';
return out_messsage;
end;
--endOfBegin
begin
select cno into course_num from course where course.cname=ip_cname;
exception
when no_data_found then
course_num:='';--私有数据的赋值方法和过程类似
out_messsage:='No such a Course';
return out_messsage;
when others then
out_messsage:='Error';
return out_messsage;
end;
--endOfBegin
begin
select 1 into tempt_count from sc where sc.sno=student_num and sc.cno=course_num;
exception
when no_data_found then
tempt_count:=0;
when others then
out_messsage:='Error';
return out_messsage;
end;
--endOfBegin
if tempt_count=1 then
begin
update sc set sc.grade=ip_grade where sc.sno=student_num and sc.cno=course_num;
--注意下面的commit语句，在update，insert时，不要忘记了哦
commit;
out_messsage:='Update Success';
return out_messsage;
exception
when others then
out_messsage:='Error';
return out_messsage;
end;
end if;
--endOfIf
if tempt_count=0 then
begin
insert into sc values(student_num,course_num,ip_grade);
commit;
out_messsage:='Insert Success!';
return out_messsage;
exception
when others then
out_messsage:='Error';
return out_messsage;
end;
end if;
--endOfIf
end;
两个例子，建表的语句请见另一篇博文
