METHOD AND DEVICE FOR ARITHMETIC OPERATION AT RETRIEVAL OF DATA BASE

摘要

PURPOSE:To shorten the processing time with the method and device by converting the attributes of such elements as the designation of a variable, the designation of a column, a constant, etc., at the terminal of an assembly of nodes of a tree structure and executing all operations with operation of a fixed attribute and with no conversion of attributes required. CONSTITUTION:A node attribute deciding means 104 refers to the pointers to the left and right operands and processes these operands as the subject nodes via a node attribute deciding means 104 as long as both pointers include no null value. A node attribute changing means 105 changes the attributes between the left and right operands based on the attribute of the subject node and the type of an operator. Then the pointers to both operands are checked and the means 105 processes these operands as the subject nodes as long as those pointers include no null value. Thus it is possible to reduce the attribute converting frequency and also to dissolve the complexity of operations.