visualises the aforementioned mapping example. The boxes contain the types declared inside the scope of J% (Java
types) and SQL. We declare types in the Java type system, which have a one-to-one relation with the correspondent SQL types.
Then, we associate them with the Java types marked as “mapped” to provide the mapping information and conversion
functions. The arrowheads illustrate the conventions that are used.
Table 4 lists all the compatible and dominant types for the SQL module. So far, the module supports on MySQL data types.1
Each database backend should have its own custom type mapping rules, since it is common for RDBMS's to have unique data
types. The types listed on the table provide the basic mapping between Java and MySQL. SQL sets and Java collections and
composite types are also supported (see Section 4.6).