While quot;nowquot; is expressed in SQL as CURRENT-TIMESTAMP within queries, this value cannot bestored in the database … database-resident variables, such asquot;now,quot; quot;until-changed,quot; quot;acirc; ,quot; quot;@quot; and quot …;-.quot; Time variables are very desirable, but their usealso leads to a new type of database, consisting of tuples with variables …