单选题A UDT is a data type which:（）A must contain unique values.B cannot be CAST to other data types.C is created using the CREATE DISTINCT command.D contains a value that was automatically calculated from values in other columns.
题目
单选题
A UDT is a data type which:（）
A
must contain unique values.
B
cannot be CAST to other data types.
C
is created using the CREATE DISTINCT command.
D
contains a value that was automatically calculated from values in other columns.