有关正确及错误的"PL/SQL"对照使用示例

/**

关于正确及错误PL/SQL对照使用的示例

*/

create table test(tid int  primary key not null,tname varchar2(50));

create sequence test_seq start with 1 increment by 1;

insert into test values(test_seq.nextval,"FLB");

insert into test values(test_seq.nextval,"FLB1");

---------------------------------

--错误函数1

create or replace function f

return int

begin

       return 5*5;

end;

--错误函数2

create or replace function f()

return number

is

begin

       return 5*5;

end;

--错误函数3

create or replace function f

return number

begin

       return 5*5;

end;

--该函数的正确函数1

create or replace function f

return number

is

begin

       return 5*5;

end;

--该函数的正确函数2

create or replace function f

return int

is

begin

       return 5*5;

end;

------------------------------------

--正确函数

create or replace function f5

(pid number)

return varchar2

is

     rname varchar2(50);

     cursor cname

     is

     select tname from test where tid=pid;

begin

     open cname;

     fetch cname into rname;

     

     return rname;

end;

--调用函数用call出错

call f5(2);

--调用出错，函数必须有值的接收者

begin

     f5(2);

end;

--这种方法调用不正确

declare

r varchar2;

begin

     r:=f5(2);

     dbms_output.put_line(r);

end;

--这种方法调用正确

begin

     dbms_output.put_line(f5(2));

end;

--这种方法调用正确

declare

r varchar2(50);

begin

     r:=f5(2);

     dbms_output.put_line(r);

end;

--正确函数

create or replace function f4

(ttid in integer)

return varchar2

is

       rname varchar(50);

       cursor cname

       is 

       select tname from test where tid=ttid;

begin

       open cname;

       fetch cname into rname;

       return rname;

end;

--正确函数

create or replace function f7

(n in number)

return number

is

begin

       return n*n;

end f7;

------------------------------------------

--过程

create or replace procedure p1

is

begin

      dbms_output.put_line("First Procuder");

end p1;

--调用过程用call不会出错

call p1();

--这种方法调用过程不正确

begin

     dbms_output.put_line(p1());

end;

----------注意函数与过程的调用的不同处----------

------------------------------------------------

--错误过程

create or replace procedure p3

(ttid in Integer)

is

       rname varchar;

       cursor cname

       is 

       select tname from test where tid=ttid;

begin

       open cname;

       fetch cname into rname;

       dbms_output.put_line(rname);

end;

--正确过程

create or replace procedure p3

(ttid in Integer)

is

       rname varchar(50);

       cursor cname

       is 

       select tname from test where tid=ttid;

begin

       open cname;

       fetch cname into rname;

       dbms_output.put_line(rname);

end; 
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