Joining Data Sources

A query may use data from multiple data sources, though it must always publish data to a single data source. Using multiple data sources in a single query is handled by an operation called a join.

In this section, the following topics will be covered:

• Stream/Window Joins.

• Using Stream Aliases.

• Window/Window Joins.

• Joins with Subqueries.

• Self-Joins.

• Joining a Stream to a Window
  A description of how to create an inquiry stream which receives a row whenever an inquiry is required. The row contained in this stream can be joined to a window which holds the desired data.
• Aggregators in a Stream/Window Join
  An example of a join query that publishes the symbol and the volume weighted average price (VWAP) for a stock over a limited period. Describes the InquiryPrice stream and schema.
• Joining Multiple Windows
  Joins can also be performed with two or more windows. Unlike stream to window joins, window-to-window joins produce data any time a row enters any of the windows.
• Joining Data Sources Using Subqueries
  Use subqueries to feed data to a subsequent query.
• Joining a Data Source to Itself (Self-Join)
  The same data source may be referenced more than once in the FROM clause by using different aliases for each copy of the same data source.

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Created March 8, 2010. Send feedback on this help topic to Sybase Technical Publications: pubs@sybase.com