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This type is used when it is necessary to describe complex relations between the records of two tables. With such a relation, records in one table can be correlated with multiple records in another table. For example, the User (user) and Group (sys_group) tables can contain multiple records of users and groups. A user can be in more than one group and a group can contain multiple users. In this case these two tables must be related using the "many-to-many" relation. In SimpleOne, the "many-to-many" relation is implemented as a separate table, that describes the way the records in two tables are related to each other. These tables are This type of relation is also used in the extended data model : they are used to create attribute collections.
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