Query language
FetchXML is the proprietary query language of Microsoft Dynamics CRM.
Which has been renamed to Microsoft Dynamics 365 Customer Engagement.
Which has transformed into the Common Data Service for the Power Platform.
Through all these transitions, FetchXML has persisted as the go-to query language for the platform.
SQL
FetchXML can be explained as the “select equivalent of SQL”. Granted, SQL is a much more colorful querying language, with full CRUD capabilities as well as functions, stored procedures etc. FetchXML does not compare to SQL in that way.
But it reads data from the Common Data Service natively. And it does it well.
Schema
There is a schema for the query syntax which has been polished and updated over the years, adding new features and capabilities. If you’re into the techy side of FetchXML – check out this schema.