The "sql" command:

Usage: fossil sql ?OPTIONS?

Run the standalone sqlite3 command-line shell on DATABASE with SHELL_OPTS.
If DATABASE is omitted, then the repository that serves the working
directory is opened.  See https://www.sqlite.org/cli.html for additional
information.

Options:

   --no-repository           Skip opening the repository database.

   -R REPOSITORY             Use REPOSITORY as the repository database

WARNING:  Careless use of this command can corrupt a Fossil repository
in ways that are unrecoverable.  Be sure you know what you are doing before
running any SQL commands that modify the repository database.

The following extensions to the usual SQLite commands are provided:

   content(X)                Return the content of artifact X.  X can be an
                             artifact hash or prefix or a tag.

   compress(X)               Compress text X.

   decompress(X)             Decompress text X.  Undoes the work of
                             compress(X).

   checkin_mtime(X,Y)        Return the mtime for the file Y (a BLOB.RID)
                             found in check-in X (another BLOB.RID value).

   symbolic_name_to_rid(X)   Return the BLOB.RID corresponding to symbolic
                             name X.

   now()                     Return the number of seconds since 1970.

   REGEXP                    The REGEXP operator works, unlike in
                             standard SQLite.

   files_of_checkin(X)       A table-valued function that returns info on
                             all files contained in check-in X.  Example:
                               SELECT * FROM files_of_checkin('trunk');