Labelling in plsql

Question

Hi i am new to plsql
i am trying to execute a simple program using labels,but its throwing error
program :
<<label1>>
declare
x varchar2(10) := 'hello';
begin
declare
x varchar2(10) := 'there';
begin
dbms_output.put_line(label1.x || x);
end;
end label1;
Error:
<<label1>>
declare
x varchar2(10) := 'hello'
ORA-06550: line 5, column 0:
PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following:
* & = - + ; < / > at in is mod remainder not rem
<an exponent (**)> <> or != or ~= >= <= <> and or like like2
like4 likec between || multiset member submultiset
8 /
begin
declare
x varchar2(10) := 'there';
begin
dbms_output.put_line(label1.x || x);
end;
end label1;
ORA-06550: line 5, column 33:
PLS-00201: identifier 'LABEL1.X' must be declared
ORA-06550: line 5, column 12:
PL/SQL: Statement ignored
it is working fine.if i wont use label in this program.
someone please help me out to resolve this problem..

Answer 1

986127 wrote:
jus wanna know labelling concepts, so tried with basic exampleI've never used it in many years of PL/SQL programming.
Labelling, I think, comes from writing spaghetti code - nested blocks, using goto statements, etc.
What labelling does show though, is the importance of explicit scope. When you have object name collisions (same name used by different code blocks/objects), you need to rather explicitly specify the scope, than leave it for the compiler to figure it out (and potentially incorrectly).
However, actual labels are not needed. Simplistic example. Table object uses empno as column name and stored proc uses empno as variable name:
SQL> create or replace procedure GetEmployee( c out sys_refcursor, empno emp.empno%Type ) is
  2  begin
  3          --// uses explicit scope to distinguish between empno as column and
  4          --// empno as parameter
  5          open c for
  6          select
  7                  e.*
  8          from    emp e
  9          where   e.empno = GetEmployee.empno;
10  end;
11  /
Procedure created.
SQL>
SQL> var c refcursor
SQL> exec GetEmployee( :c, 7902 );
PL/SQL procedure successfully completed.
SQL> print c
     EMPNO ENAME      JOB              MGR HIREDATE                   SAL       COMM     DEPTNO
      7902 FORD       ANALYST         7566 1981/12/03 00:00:00       3000                    20
SQL> There is a somewhat misguided standard used in PL/SQL, based on (outdated and flawed) Hungarian notation, that states that parameters need to be prefixed using "+p_+" and variables using "+v_+".
But is a superfluous standard. The PL/SQL language supports explicit scope resolution. There's no reason to reinvent that, and reinvent it poorly and inconsistently, using a Hungarian notation style standard.