UPDATE target[ [  AS  ]  alias] 
SET col= newval[, col= newval...] 
. . .

MERGE INTO target[ AS  target_alias] 
USING <source>[ AS  source_alias] 
ON <join condition>
<merge when>[<merge when>...] 
. . .

select
        t.mon$table_name
        ,r.mon$record_inserts
        ,r.mon$record_updates
        ,r.mon$record_deletes
        ,r.mon$record_backouts
        ,r.mon$record_purges
        ,r.mon$record_expunges
        -----------
        ,r.mon$record_seq_reads
        ,r.mon$record_idx_reads
        ,r.mon$record_rpt_reads
        ,r.mon$backversion_reads
        ,r.mon$fragment_reads
        -----------
        ,r.mon$record_locks
        ,r.mon$record_waits
        ,r.mon$record_conflicts
        ------------
        ,a.mon$stat_id
    from mon$record_stats r
    join mon$table_stats t on r.mon$stat_id = t.mon$record_stat_id
    join mon$attachments a on t.mon$stat_id = a.mon$stat_id
    where
        a.mon$attachment_id = current_connection
    ;

select
        -- mon$io_stats:
         i.mon$page_reads
        ,i.mon$page_writes
        ,i.mon$page_fetches
        ,i.mon$page_marks
        -- mon$record_stats:     
        ,r.mon$record_inserts
        ,r.mon$record_updates
        ,r.mon$record_deletes
        ,r.mon$record_backouts
        ,r.mon$record_purges
        ,r.mon$record_expunges
        ,r.mon$record_seq_reads
        ,r.mon$record_idx_reads
    
        ,r.mon$record_rpt_reads
        ,r.mon$backversion_reads
        ,r.mon$fragment_reads
    
        ,r.mon$record_locks
        ,r.mon$record_waits
        ,r.mon$record_conflicts
        ------------------------
        ,u.mon$memory_used
        ,u.mon$memory_allocated
        ,a.mon$stat_id
        ,a.mon$server_pid
    from mon$attachments a
    left join mon$memory_usage u on a.mon$stat_id=u.mon$stat_id
    left join mon$io_stats i on a.mon$stat_id=i.mon$stat_id     
    left join mon$record_stats r on a.mon$stat_id=r.mon$stat_id     
    where     
      a.mon$attachment_id = current_connection
   ;

SELECTMON$ISOLATION_MODE
FROMMON$TRANSACTIONS
WHEREMON$TRANSACTION_ID = CURRENT_TRANSACTION

rdb$get_context('SYSTEM','ISOLATION_LEVEL')

select a.* 
from mon$attachments a 
join mon$transactions t using (mon$attachment_id) 
where NOT (t.mon$read_only=1 and t.mon$isolation_mode>=2 );

Statement failed, SQLSTATE = 22003
arithmetic exception, numeric overflow, or string truncation
-numeric value is out of range