There are 2 tables. The first table is Product, the second is Calls. Both tables have phone numbers. They may or may not be the same. In the Product table, there may be less phones than in the Calls table. The main table is Calls. The task is to search the phone in the field using two tables at the same time and no difference if there is such a phone in one table and no one in the other. This is necessary in order to understand by the telephone number whether there are goods associated with such a telephone number (the Product table) and whether there were calls to this telephone number (the Calls table).
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