public Class DBMDWrapper

OptionalTool to create wrapper functions which allow you to invoke DatabaseMetaData methods via SQL. The wrapper functions slightly change the signature of the metadata methods as follows:

• Arguments of type int[] and String[] have been eliminated--they are automatically wildcarded.
• The method getRowIdLifetime() has been commented out--Derby does not support object types.
• The method getSchemas() has been commented out--it can be uncommented when the registration logic is made smarter to handle the dropping of different overloads.
• The method supportsConvert() has been commented out because Derby only allows one function by a given name and the supportsConvert( int, int ) overload is more general.

Methods which return ResultSet are mapped to table functions. You can join the metadata table functions like this:

-- list all of the columns in the connected Derby database
select t.table_schem, t.table_name, c.column_name, c.type_name
from table( getTables( null, null, null ) ) t,
        table( getColumns( null, null, null, null ) ) c
where c.table_schem = t.table_schem
and c.table_name = t.table_name
and t.table_type = 'TABLE'
;


-- now list metadata in a foreign database
call setDatabaseURL( 'com.mysql.jdbc.Driver', 'jdbc:mysql://localhost/world?user=root&password=' );

select t.table_schem, t.table_name, c.column_name, c.type_name
from table( getTables( 'WORLD', null, null ) ) t,
        table( getColumns( 'WORLD', null, null, null) ) c
where c.table_name = t.table_name
and t.table_type = 'TABLE'
;

-- release the foreign connection
call setDatabaseURL( '', '' );