单项选择题
If a unique constraint is defined on column COL1 of table TAB1, what are the characteristics of COL1?（）
A.COL1 will accept NULL values and can be referenced in another table's foreign key specification.
B.COL1 will not accept NULL values and cannot be referenced in another tables foreign key specification.
C.COL1 will not accept NULL values and can be referenced in another tables foreign key specification.
D.COL1 will accept NULL values and cannot be referenced in another tables foreign key specification.
相关考题
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单项选择题
A DBA has been asked to create a table which will contain a substantial amount of detailed sales information for each calendar month and maintain it to contain only the last 12 months. Which of the following methods will facilitate the online removal of the oldest month’s data?（）
A.Create an MQT that selects the oldest month of data with the REFRESH IMMEDIATE option.
B.Create 12 separate tables, create a view based on all 12, drop the table with the oldest month's data then drop and re- create the view.
C.Create a range partitioned table, partitioned by month, and use the ALTER TABLE statement to detach the oldest month and attach storage for new data.
D.Create a single table, extract the data to be retained using UNLOAD with a SELECT statement, drop and re-create the table then load only the data to be retained. -
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. -
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.
