单项选择题
Which of the following is true of an index used to support a UNIQUE constraint?（）
A.It must have the UNIQUE attribute.
B.It cannot be created explicitly by the user.
C.It must have the UNIQUE and CLUSTER attributes.
D.It must have the UNIQUE WHERE NOT NULL attribute.
相关考题
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单项选择题
A view is created with the following statement:CREATE VIEW v1 AS SELECT col1, col2, col3, col4 FROM t1 WHERE col4 > 1000 WITH CHECK OPTIONWhat is the effect of the CHECK OPTION clause?（）
A.Any row inserted or updated through view V1 must meet the condition that col4 > 1000.
B.From now on, any row inserted or updated in table T1 must meet the condition that col4 > 1000, but existing rows in the table are not checked.
C.At view creation, DB2 will check the data in table T1, and if in any row doesn't meet the condition col4 > 1000, the view creation will be rejected.
D.Any row inserted or updated through view V1 must meet the condition that col4 > 1000 and no row in table T1 can be updated such that col4 <= 1000, but new rows in the table can be inserted with col4 <= 1000. -
单项选择题
Which of the following are all valid DB2 data types?（）
A.LONG VARCHAR, SMALLINT, NUMBER, BLOB
B.DECIMAL, DATE, DBCLOB, INTERVAL
C.NUMERIC, TIMESTAMP, BYTE, FLOAT
D.NUM, TIME, XML, DOUBLE -
单项选择题
What type of constraint can be used to ensure that, in any given row in a table, the value of one column never exceeds the value of another column?（）
A.Check
B.Range
C.Referential
D.Informational
