master data table is not changes frequently but transactional data table will change frequently. master data records will be less compared to transactional data records.
customer table ie KNA1 is Master data table and VBAK ie sales order header table is transactional data table.
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example is the material stock of a warehouse,
which can change after each purchase order.
varchar or text should be the best datatypes for storing mobile numbers
Maximum length of 8,000 characters.( Fixed length non-Unicode characters)
varchar Maximum of 8,000 characters.(Variable-length non-Unicode data).
To Store "Country + area + number separately". You can try using a VARCHAR(20), this allows you the ability to store international phone numbers properly, should that need arise.