joinlist — aggregate function to convert an input list to a string with optional separator.
This function is an alias for the aggregate version of the join() function in the StreamBase expression language. The alias name differentiates the join() function from the JOIN keyword, which is a reserved keyword in LiveQL.
This function takes a string argument to specify the separator to place between list items, and the name of a list whose data type is one of the supported LiveView data types.
This function was added as a LiveView aggregate function primarily to allow the unique() function to be used in author-time aggregations. unique() returns a list, and LiveView columns cannot be sourced from a list; thus, to use unique() in an author-time aggregation projection, you must wrap unique() with joinlist(), as in the folowing example usable with the Hello LiveView sample:
select joinlist(",", unique(Severity, 5)) as SeverityList from LVAlerts