Triggering can only be used by setting it on your input PCollections; there are no SQL extensions for specifying triggering.
This section covers the use of SQL extensions to directly apply windowing.
Beam SQL supports windowing functions specified in GROUP BY clause. TIMESTAMP field is required in this case. It is used as event timestamp for rows.
Note: when no windowing function is specified in the query, then windowing strategy of the input PCollections is unchanged by the SQL query. If windowing function is specified in the query, then the windowing function of the PCollection is updated accordingly, but trigger stays unchanged.