Use SELECT to retrieve data

The most common AVEVA Historian query is a SELECT statement:

SELECT select_list

FROM table_source

WHERE search_condition

[ GROUP BY group_by_expression ]

[ HAVING search_condition ]

[ ORDER BY order_expression [ ASC | DESC ] ]

A WHERE clause is mandatory when issuing a SELECT query against any extension table except HistoryBlock.

There are four variations for issuing a SELECT statement to the AVEVA Historian OLE DB provider to retrieve history data:

• Use the four-part naming convention

• Use an AVEVA Historian OLE DB provider view

• Use the OPENQUERY function

• Use the OPENROWSET function

You should use the four-part name or a provider view to specify the extension table, whenever possible. However, there are instances when the OPENQUERY or OPENROWSET function must be used, such as for queries on wide tables.

For general information on creating SQL queries, see your Microsoft SQL Server documentation.