/ modules / paradigms / Numeric_Straight.py 

 SYNOPSIS

     Numeric_Straight (table, idColumn, valueColumn, units, cardinality)

         table
             A table to query, e.g., "holding".

         idColumn
             The table's object identifier column (i.e., the column
             to be selected), e.g., "holding_id".

         valueColumn
             The table's value column (i.e., the column against which
             the constraint is to be placed), e.g., "resolution".

         units
             A dictionary that maps units of measure (as strings) to
             multiplicative conversion factors (as floats).  For
             example, if the value column is stored in meters, the
             units dictionary might be:

                 { "meters"      : 1.0,
                   "centimeters" : 0.01,
                   "inches"      : 0.0254 }

         cardinality
             A Cardinality object representing the cardinality of
             'table' with respect to 'valueColumn'.

 DESCRIPTION

     Translates a numeric constraint to an SQL numeric comparison.

     Given a numeric constraint (B, O, V [, U]) where B is a numeric
     bucket, O is one of the six standard relational operators, V is
     a real number, and U is an optional unit of measure, this
     paradigm converts V to the unit of measure used by the table's
     value column and returns the following query:

         SELECT idColumn FROM table
             WHERE valueColumn op Vconv

     where 'op' is the SQL equivalent of O and 'Vconv' is the
     converted value of V.

     Exceptions thrown:

         unsupported unit of measure

 AUTHOR

     Greg Janee
     gjanee@alexandria.ucsb.edu

 HISTORY

     $Log: Numeric_Straight.py,v $
     Revision 1.1  2002/10/01 18:30:53  gjanee
     Initial revision