Think of a multi-valued column as a single-column nested table. If you prefer, a cell whose data type is 'table'. This is a simple enough concept in XML; the Pick model has had it since the 1960's!
The sum of all elements in a multi-valued column is given by the SUM() function if there are no sub-values, or by the SUMMATION() function if there are sub-values. A sub-value is the next level of division; where a field (cell) can contain multiple values, each of those values can contain multiple sub-values. A multi-valued field is already an array - a "dynamic array". You can get the nth value from a multi-valued field using "angle bracket" notation, for example StageList<1,n> - which means "the nth value in the first field of StageList". Statements in the BASIC programming language exist for converting between dynamic arrays and dimensioned arrays (MATPARSE/MATBUILD), between dynamic arrays and Select Lists (READLIST/FORMLIST), and between dynamic arrays and delimited strings (CONVERT). It is also possible to have "associated multi-valued columns" in which a one-to-one relationship is preserved between the values in the fields in the association. Think of this as a multi-column nested table. Again it is an easy concept to represent using that new kid on the block, XML. ------- u2-users mailing list [email protected] To unsubscribe please visit http://listserver.u2ug.org/
