SQL Reference

Table Expressions

A table expression creates a (temporary) result table from a simple query. Clauses further refine the result table. For example, a table expression could be a query that selects all the managers from several departments and further specifies that they have over 15 years of working experience and are located at the New York branch office.

Common Table Expressions

A common table expression is like a temporary view within a complex query, and can be referenced in other places within the query; for example, in place of a view, to avoid creating the view. Each use of a specific common table expression within a complex query shares the same temporary view.

Recursive use of a common table expression within a query can be used to support applications such as bill of materials (BOM), airline reservation systems, and network planning. A set of examples from a BOM application is contained in Appendix M, Recursion Example: Bill of Materials.


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