7.1.4 Data Type Conformance on IN Parameters

The data type in a setter method is a type in the Java programming language. It also implicitly specifies a JDBC type because the driver will map the Java type to its corresponding JDBC type (following the mapping specified in "Java Types Mapped to JDBC Types" on page 129) and send that JDBC type to the database. For example, the following code fragment sets the second parameter of the PreparedStatement object pstmt to 44, with a Java type of short:
pstmt.setShort(2, 44);
The driver will send 44 to the database as a JDBC SMALLINT, which is the standard mapping from a Java short.
It is the programmer's responsibility to make sure that the type in the Java programming language for each IN parameter maps to a JDBC type that is compatible with the JDBC data type expected by the database. Consider the case where the database expects a JDBC SMALLINT. If the method setByte is used, the driver will send a JDBC TINYINT to the database. This will probably work because many database systems convert from one related type to another, and generally a TINYINT can be used anywhere a SMALLINT is used. However, for an application to work with the most database systems possible, it is best to use types in the Java programming language that correspond to the exact JDBC types expected by the database. If the expected JDBC type is SMALLINT, using setShort instead of setByte will make an application more portable. The table "Java Types Mapped to JDBC Types" in the chapter "Mapping SQL and Java Types" can be used to determine which setter method to use.