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== Controlling scope with a variable declaration==

By definition, the scope of a variable is a region of a program unit from which you can reference the variable.
A variable is local to the block where it is declared.
A variable is global to all sub-blocks of the block where it is declared.
In the following code, variable V_STR1_main is local for the block labeled <<MAIN>> and global for the
block labeled <>. Variable V_STR1_sub is visible only in the block <>.



<source lang="sql">
SQL> <<MAIN>>
2 declare
3 v_str1_main VARCHAR2(10);
4 begin
5 v_str1_main :="ABC"; -- local
6 <>
7 declare
8 v_str1_sub VARCHAR2(1);
9 begin
10 v_str1_main:="ABC"; -- local
11 v_str1_sub:="A"; -- global and visible
12 end;
13 v_str1_main :="ABC"; -- local
14 end;
15 /
PL/SQL procedure successfully completed.
SQL></source>

== Scope Rules==

<OL><LI>Scope means the range of code within which a given identifier can be referenced.</LI><LI>An identifier can be referenced only by code executing inside the block in which the identifier was declared.</LI><LI>An identifier could be a variable name, or a procedure name, function name.</LI></OL>
The following example illustrates the scope of various identifiers.



<source lang="sql">
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 a_name VARCHAR2(30) := "James";
3 PROCEDURE name_print IS
4 BEGIN
5 DBMS_OUTPUT.PUT_LINE(a_name);
6 END;
7
8 BEGIN
9 DBMS_OUTPUT.PUT_LINE(a_name);
10 DECLARE
11 b_name VARCHAR2(30) := "Jenny";
12
13 BEGIN
14 DBMS_OUTPUT.PUT_LINE("Inside nested block");
15 DBMS_OUTPUT.PUT_LINE(a_name);
16 DBMS_OUTPUT.PUT_LINE(b_name);
17 name_print;
18 END;
19 DBMS_OUTPUT.PUT_LINE("Back in the main block");
20 --b_name is not defined in this block.
21 --DBMS_OUTPUT.PUT_LINE(b_name);
22 name_print;
23 END;
24 /
James
Inside nested block
James
Jenny
James
Back in the main block
James
PL/SQL procedure successfully completed.
SQL></source>

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