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Properties of Tables

19 十月, 2015 - 15:32
  • Table has a name that is distinct from all other tables in the database.
  • There are no duplicate rows, each row is distinct.
  • Entries in columns are atomic (no repeating groups or multivalued attributes)
  • Entries from columns are from the same domain based on their data type:

number (numeric, integer, float, smallint,…)

character (string)

date

logical (true or false)

  • Operations combining different data types are disallowed
  • Each attribute has a distinct name
  • sequence of columns is insignificant
  • sequence of rows is insignificant