A.must contain unique values.B.cannot be CAST to other ……

单项选择题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.

单项选择题Which of the following DB2 data types has a fixed length?（）

A.XML
B.BLOB
C.DOUBLE
D.DBCLOB

单项选择题Which of the following actions may cause a trigger to be fired?（）

A.DROP
B.ALTER
C.DELETE
D.ROLLBACK

单项选择题What type of constraint is used to ensure that each row inserted into the EMPLOYEE table with a value in the WORKDEPT column has a row with a corresponding value in the DEPTNO column of the DEPARTMENT table?（）

A.A check constraint on the EMPLOYEE table
B.A unique constraint on the EMPLOYEE table WORKDEPT column
C.A foreign key reference from the DEPARTMENT tables DEPTNO column to the WORKDEPT column of the EMPLOYEE table
D.A foreign key reference from the EMPLOYEE tables WORKDEPT column to the DEPTNO column of the DEPARTMENT table

单项选择题Which of the following constraint types can be used to ensure the value of an INTEGER column references only positive values?（）

A.Unique
B.Check
C.Referential
D.Informational