Hi all, is it possible to use a mapping file (and the related Java class) to access more than one table? For instance, is it possible to dynamically change the "class" attribute in the mapping file?

Thanks,
Jeff

I take it that you don't mean a Java class that is mapped to a join of two tables, which is quite possible. If you mean changing the mapping at runtime, that might be possible. Explain you situation a bit more.

I have more or less 350 different tables... but all of them have a column named ID. I'm developing a tool for determining the most appropriate ID for each table according to some predefined rules.

For instance, I don't want to have 350 identical mapping files and as many identical Java classes just because I'm accessing 350 tables. One mapping file and one Java class should be fine for such a task.

Talk 2 u soon,
Jeff

Just because all of the tables have a column named ID does not mean one mapping file can be used for all of them. I assume each table has a slightly different set of columns, otherwise why not put all the data in one table.

If you want to use Hibernate in Java, and you will access more than one of the tables you will need to create a mapping for each table that you want to access.

For instance, let's say you have 5 tables, A,B,C,D,and E. Each one has a column called ID and also has other columns, let's say A has a1, a2, a3; B has b1, b2, b3, etc. Now if you want to access table A from Java you need to create a mapping file (or use annotations) that map the columns in A to instance variables in a Java class. Same for B, C, D, and E. Each table will need its own mapping file and corresponding Java class.

There are some tools that might allow you to reverse engineer your database schema into a set of mapping files and Java objects. I haven't used them.

Feel free to give more details if what I said does not really capture your issue.

I take it you would be determining at runtime within the JRE which mapping to call right? If that is the case could you use entity-name's?

For Example:


And your Java code: