.EDMX File Extension
File TypeADO.NET Entity Data Model Designer File
What is an EDMX file?
Data model file created by the Entity Data Model Designer component of Microsoft Visual Studio; stores the schema for a database, including entities (e.g., database tables), their fields, and their relationships (e.g., one-to-one and one-to-many).
EDMX files are used for generating SQL Server database schemas. They contain three metadata files: 1) the conceptual schema definition language (CSDL) file, 2) the store schema definition language (SSDL) file, and 3) the mapping specification language (MSL) file.
NOTE: To create EDMX files, you need a version of Visual Studio that includes the ADO.NET Entity Data Model Designer.