When dynamic schema is enabled, Windows Azure Mobile Services automatically generates new columns based on the JSON object in the insert or update request. Once a column is created, its data type cannot be changed. Insert or update operations will fail when the type of a property in the JSON object cannot be converted to the type of the equivalent column in the table.
Dynamic schema is enabled by default. With dynamic schema, you do not need to specify column names or their types. New columns are automatically created based on the data in insert or update requests. When a column with the same name does not already exist, a column is created with the data type inferred based on the property of the received JSON object.
Important: We recommend that you disable dynamic schema support before publicly releasing your app.
Once a column has been created, Mobile Services cannot change the data type of the column. To do this, you must modify the SQL Database directly.