established, most of the time the only code which change is either SQL 

statements or return data types.

The JDBC API does not put any restrictions on the kinds of SQL statements that 

can be executed though JDBC, so it is the application's responsibility to pass 

SQL statements compatible to the database used.

The connection obtained in 

Example 7 38 and Example 7 39 can be used for one of the following three types 

of statements depending upon the requirements:

Statement   Simple single SQL statement

The statement can be created by using the 

createStatement

 method of the 

Connection. Example 7 40 shows the usage of 

executeQuery

 with a change 

for MySQL and DB2 UDB. As we can see in the example the only change in 

this code is the SQL statement.

Example 7 40   Query statement changes from MySQL to DB2 UDB

Statement s = conn.createStatement();

//MySQL statement

s.executeQuery ("SELECT warenkorb.wk_id, warenkorb.user_id,warenkorb.status 

FROM warenkorb"); 

//DB2 UDB statement

s.executeQuery ("SELECT wk_id, user_id,status FROM itsodb.warenkorb"); 

ResultSet rs = s.getResultSet ();

while (rs.next ())

   {

       int id = rs.getInt ("wk_id");

       int uid = rs.getInt("user_id");

       String status = rs.getString ("status");

       System.out.println (

               "id = " + id

               + ", user = " + uid

               + ", status = " + status);

   }

   rs.close ();

   s.close ();

PreparedStatement   Precompiled SQL statements

PreparedStatements are used to effectively execute the statement multiple 

times. Example 7 41 shows the conversion of the prepared statements. 

Setting appropriate values of host variables is very important while using 

prepared statements. In the section titled  Java, JDBC, and SQL data type 

conversions  on page 197 we discuss more about it.

callableStatement   Statement to call stored procedures (only in DB2 UDB)

194 

MySQL to DB2 UDB Conversion Guide