Java Reference
In-Depth Information
Two further set operators are supported by some SQL dialects. These are the EXCEPT operator, and
the INTERSECT operator, which are discussed in the following paragraphs.
EXCEPT Operator
The
EXCEPT
operator creates a result set by including all rows returned by the first query but not
returned by the second query. The default version eliminates all duplicate rows, but
EXCEPT ALL
does
not.
INTERSECT Operator
The
INTERSECT
operator creates a result set by including only rows that exist in both queries and by
eliminating all duplicate rows. When you use
ALL
with
INTERSECT
, the duplicate rows are not
eliminated.
Summary
In this chapter, you learn about the following topics:
INNER JOINS
and
OUTER JOINS
EQUI-JOIN
s
NON-EQUI-JOIN
s
OUTER JOIN
s
LEFT OUTER JOINS
RIGHT OUTER JOINS
FULL OUTER JOINS
SELF-JOINS
Cartesian Products
The
UNION
operator
The
next chapter
discusses MetaData and moves on to combine the topics discussed thus far to build
a complete client/server application.
