Modifying DEFAULT clause column definitions
The DEFAULT clause provides a default value for a column in the event that a value is not supplied on INSERT or is specified as DEFAULT on INSERT or UPDATE. If a specific default value is not specified following the DEFAULT keyword, the default value depends on the data type. If a column is defined as an XML or structured type, then a DEFAULT clause cannot be specified.
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Specific types of values that can be specified with the DEFAULT keyword, see the ALTER TABLE statement.