Oracle PL/SQL/PL SQL/subtype

Create a constrained subtype DB_STRING

   <source lang="sql">
   

SQL> SQL> DECLARE

 2    SUBTYPE db_string IS VARCHAR2(4000 BYTE);
 3    c VARCHAR2(1 CHAR) := "A";
 4    d DB_STRING;
 5  BEGIN
 6    d := c;
 7  END;
 8  /

PL/SQL procedure successfully completed. SQL> SQL>

 </source>
   
  

Creates and uses a constrained subtype CODE

   <source lang="sql">
   

SQL> SQL> DECLARE

 2    SUBTYPE code IS CHAR(1 CHAR);
 3    c CHAR(1 CHAR) := "A";
 4    d CODE;
 5  BEGIN
 6    d := c;
 7  END;
 8  /

PL/SQL procedure successfully completed. SQL>

 </source>