PLSQL CASE - WHEN - THEN - END CASE.

CASE selecteur
   WHEN expression1 THEN instruction1;
   WHEN expression2 THEN instruction2;
   …
   WHEN expression3 THEN instruction3;
   ELSE instruction4;
END CASE;

SQL> SET SERVEROUTPUT ON
SQL> DECLARE
       var_cp VARCHAR2(5) := '83000';
     BEGIN
       var_cp := SUBSTR(var_cp,1,2);
       CASE var_cp
         WHEN '78' THEN DBMS_OUTPUT.PUT_LINE ('Département Yvelines');
         WHEN '94' THEN DBMS_OUTPUT.PUT_LINE ('Département Val de Marne');
         WHEN '83' THEN DBMS_OUTPUT.PUT_LINE ('Département Var');
         ELSE           DBMS_OUTPUT.PUT_LINE ('Département Autre');
       END CASE;
     END;
     /
Département Var

Procédure PL/SQL terminée avec succès.

SQL>

CASE
   WHEN condition1 THEN instruction1;
   WHEN condition2 THEN instruction2;
   …
   WHEN condition3 THEN instruction3;
   ELSE instruction4;
END CASE;

SQL> SET SERVEROUTPUT ON
SQL> DECLARE
       var_cp VARCHAR2(5) := '75000';
     BEGIN
       CASE
         WHEN SUBSTR(var_cp,1,2) = '78' THEN DBMS_OUTPUT.PUT_LINE ('Département Yvelines');
         WHEN SUBSTR(var_cp,1,2) = '94' THEN DBMS_OUTPUT.PUT_LINE ('Département Val de Marne');
         WHEN SUBSTR(var_cp,1,2) = '83' THEN DBMS_OUTPUT.PUT_LINE ('Département Var');
         ELSE                                DBMS_OUTPUT.PUT_LINE ('Département Autre');
       END CASE;
     END;
     /
Département Autre

Procédure PL/SQL terminée avec succès.

SQL>