GENERATED BY DEFAULT

An identity column of type GENERATED BY DEFAULT will generate a value on insert if no value — other than DEFAULT — is specified on insert.When the OVERRIDING USER VALUE clause is specified in the INSERT statement, the user-provided value is ignored, and an identity value is generated (as if the column was not included in the insert, or the value DEFAULT was specified).

The optional START WITH clause allows you to specify an initial value other than 1.This value is the first value generated when using NEXT VALUE FOR sequence.