Decode statement could be easily rewritten using the CASE statement

   
SQL>
SQL> CREATE TABLE myCar
  2  (
  3    MAKER  VARCHAR (25),
  4    MODEL  VARCHAR (25),
  5    PRICE  NUMERIC
  6  );

Table created.

SQL>
SQL> INSERT INTO myCar VALUES('CHRYSLER','CROSSFIRE',33620);

1 row created.

SQL> INSERT INTO myCar VALUES('CHRYSLER','300M',29185);

1 row created.

SQL> INSERT INTO myCar VALUES('HONDA','CIVIC',15610);

1 row created.

SQL> INSERT INTO myCar VALUES('HONDA','ACCORD',19300);

1 row created.

SQL>
SQL> INSERT INTO myCar VALUES('FORD','MUSTANG',15610);

1 row created.

SQL> INSERT INTO myCar VALUES('FORD','LATESTnGREATEST',NULL);

1 row created.

SQL> INSERT INTO myCar VALUES('FORD','FOCUS',13005);

1 row created.

SQL>
SQL> SELECT
  2     model,
  3     DECODE(maker, 'CHRYSLER','DOMESTIC'
  4           ,'FORD','DOMESTIC'
  5           ,'FOREIGN')
  6  FROM myCar;

MODEL                     DECODE(M
------------------------- --------
CROSSFIRE                 DOMESTIC
300M                      DOMESTIC
CIVIC                     FOREIGN
ACCORD                    FOREIGN
MUSTANG                   DOMESTIC
LATESTnGREATEST           DOMESTIC
FOCUS                     DOMESTIC

7 rows selected.

SQL>
SQL> SELECT
  2        model,
  3        CASE maker
  4        WHEN 'CHRYSLER'      THEN 'DOMESTIC'
  5        WHEN 'FORD'          THEN 'DOMESTIC'
  6        ELSE                'FOREIGN'
  7        END
  8   FROM myCar;

MODEL                     CASEMAKE
------------------------- --------
CROSSFIRE                 DOMESTIC
300M                      DOMESTIC
CIVIC                     FOREIGN
ACCORD                    FOREIGN
MUSTANG                   DOMESTIC
LATESTnGREATEST           DOMESTIC
FOCUS                     DOMESTIC

7 rows selected.

SQL>
SQL> drop table myCar;

Table dropped.

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Decode statement could be easily rewritten using the CASE statement : DECODE « Conversion Functions « Oracle PL / SQL

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