Used for single-source queries, used for joins that use the JOIN syntax, and it is used for database subqueries and to remote subqueries.
The FROM clause, part of a Query Statement, Database Statement, or Remote Procedure Statement, has three syntax variations:
The FROM Clause: Comma-Separated Syntax: Used for single-source queries, and contains joins that use the comma-separated syntax and queries that use the MATCHING clause to detect patterns.
The FROM Clause: Join Syntax: Used for joins that use the JOIN syntax.
The FROM Clause: Database and Remote Subquery Syntax: Used for database subqueries and remote subqueries.