BUG: Example of Sp_addtype Is Unclear in the Documentation

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In the section on the nulltype parameter for sp_addtype, the "Transact-SQL Reference" correctly states that if a null value is specified for this parameter, the default nullability setting of the data type will be based on the current ansinull setting for the connection. You can determine what the current setting is by using the system function getansinull(); you can control the setting with the SET and sp_dboption commands.

The following command in example B is supposed to always enable the default nullability of a user-defined datatype:

   sp_addtype birthday, datetime, NULL
				

However, specifying NULL for the nulltype parameter passes a null value into sp_addtype, not the string "NULL." The command above will therefore set birthday's nullability default to the current ansinull setting. If ansinull is off, then birthday will default to not null. If you want a datatype to default to allowing nulls regardless of the current setting of ansinull, you should instead use the following command:

   sp_addtype birthday, datetime, 'NULL'