def primary_key_names(table)
if tables.grep(/^#{table}$/i).empty?
raise "table '#{table}' does not exist"
end
columns = []
result_set = @connection.connection.getMetaData.getPrimaryKeys(nil, nil, table);
while result_set.next
column_name = result_set.getString("COLUMN_NAME")
key_seq = result_set.getShort("KEY_SEQ")
columns << {:column_name => column_name, :key_seq => key_seq}
end
columns.sort! {|a, b| a[:key_seq] <=> b[:key_seq]}
key_names = columns.map {|column| column[:column_name]}
key_names
end