On DB2 you have two ways to convert DATA TYPES:

We are going to use the table below for our examples:

db2 describe table example

Output:                                                            

Column name                     schema    Data type name      Column Length     Scale      Nulls
----------------------------------- ------------ ----------------------- ----------------------------- --------- --------
COD                                     SYSIBM      INTEGER                             4                        0        Yes  
NAME                                  SYSIBM      VARCHAR                         40                        0        Yes  
ENTRANCE                       SYSIBM      DATE                                    4                         0        Yes  
VALUE                                SYSIBM      DOUBLE                               8                        0        Yes  

Data:

db2 select * from example

COD         NAME                                                   ENTRANCE    VALUE                 
----------- ---------------------------------------------- --------------------- ------------------------
     1                                              William                   10/15/2009   +3.22900000000000E+002
     2                                                       38                   12/23/2009   +4.59000000000000E+001
     3                                             Barbara                  02/03/2009   +1.43000000000000E+000
234                                                        40                  02/30/2009   +2.30000000000000E+001

FIRST WAY - USING FUNCTION CAST

Example A

db2 "select cod, cast(name as int) as name from example where name in ('38','40')"

Example B

db2 "select cast(cod as char) from example"

SECOND WAY

db2 "select cod, int(name) as name from example where name in ('38','40')"

db2 "select char(cod) from example"