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SQL NOT NULL Constraint
  • MM Loogy

SQL NOT NULL Constraint

By default, a column can hold NULL values.


The NOT NULL constraint enforces a column to NOT accept NULL values.


This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.


The following SQL ensures that the "ID", "LastName", and "FirstName" columns will NOT accept NULL values:


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