The SQL:1999 standard specifies the
<lateral derived table>, which is SQL’s way of allowing for a derived table (a subquery in the
FROMclause) to access all the lexically preceding objects in the
FROMclause. It’s a bit weird in terms of syntax, I personally think that Microsoft SQL Server has a much nicer solution for this concept via
APPLY. Oracle supports both syntaxes (standard and T-SQL’s). Db2, Firebird, MySQL, PostgreSQL only have
Click through to see how the operator works.