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StructureBasic StructureThe basic form of a simple NSQL query is: SELECT <list> FROM <list> WHERE <statement>; A query of this type will generate a set or Domain of records that satisfies the WHERE condition and contains the columns specified in the SELECT list (from the tables listed in the FROM clause).
Example QueryTo perform a query with Engine one must make a new NSQL object in the system by creating an IQuery object. Consider the following Visual Basic example: Dim Qry as IQuery Set Qry = System.NewQuery( “Select * From Customer;”) Qry.Calculate TextBox1 = Qry.RowBuffer(500,0) In this example, a new query is created in this user's ISession (called System) then calculated and the results are placed in a text box on a form. DomainsThe basic form of a Domain producing NSQL query is: SELECT [{DISTINCT},{DISTINCTROW}] <list of columns> [INTO {“FILE”} or {[DATABASE].[TABLE]}) FROM <list of tables> [WHERE <conditions>] [ORDER BY <list of columns> , [DESC]]; Statistical ValuesFor queries producing a single statistical value the format is as follows: SELECT FUNCTION(<column>) FROM <table> [WHERE <conditions>]; Where FUNCTION is one of the statistical functions defined under the section Aggregate Functions CrosstabulationsFor queries producing one or two dimensional crosstabulations: SELECT {COUNT(*)} or {FUNCTION<column>} FROM <list of tables> [WHERE <conditions>] GROUP BY <vertical axis column> [PIVOT BY <horizontal axis column>]; Each cell in the crosstab will either contain a count of records or an aggregation defined by the function FUNCTION of a particular column, FUNCTION must be one of: SUM - The sum of all cell values for the column MEAN - The average column value of each cell MIN - The minimum column value of each cell MAX - The maximum column value of each cell |
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