As it was said above, a relation is a constituent part of a simple condition. In the previous subsections examples mainly with simple relations of equality were examined.
ObjectLand permits using different relations which can be divided into four groups (table 26-1). Each group is characterized by field types for which group relations are possible and also a number of operands for specifying the simple condition.
In subsequent subsections all relations admissible for ObjectLand will be described in detail. In tables 26-2, 26-3, 26-4, 26-5 describing relations for each relation type relationship between field values and operands will be indicated in which simple condition is considered true.
Relations | Number of operands | Field types |
Comparison | One | String, integer, real, date, time, timestamp, Boolean |
Diapasons, intervals | Two | String, integer, real, date, time, timestamp, Boolean |
Existence of value | No | String, integer, real, date, time, timestamp, Boolean |
Matching the pattern | One | String, date, time, timestamp |
Table 26-1. Groups of relations
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