An MDQ file is a data file created by Database Interface Designer, which is a tool included with IBM Transformation Extender. It contains definitions for one or more databases, stored procedures, queries, and other specifications. MDQ files are used to execute Transformation Extender maps, which are visual representations of databases that include how objects are to be transformed from the source format to the target format.

To open an MDQ file in Database Interface Designer, select File → Open. To create an MDQ file in Database Interface Designer, select File → Save. IBM Transformation Extender is a program that allows users to integrate customer, business partner, and supplier transactions across an enterprise. The Database Interface Designer is a tool included with Transformation Extender and used to import metadata about stored procedures, tables, and queries from a relational database.