11. In the initial creation of a table, if a UNIQUE constraint is included for a composite column that requires the combination of entries in the specified columns to be unique, which of the following…
11. In the initial creation of a table, if a UNIQUE constraint is included for a composite column
that requires the combination of entries in the specified columns to be unique, which of the
following statements is correct?
a. The constraint can be created only with the ALTER TABLE command.
b. The constraint can be created only with the table-level approach.
c. The constraint can be created only with the column-level approach.
d. The constraint can be created only with the ALTER TABLE … MODIFY command.
12. Which type of constraint should you use on a column to allow entering only values above 100?
a. PRIMARY KEY
b. UNIQUE
c. CHECK
d. NOT NULL
13. Which of the following commands can be used to enable a disabled constraint?
a. ALTER TABLE … MODIFY
b. ALTER TABLE … ADD
c. ALTER TABLE … DISABLE
d. ALTER TABLE … ENABLE
14. Which of the following keywords allows the user to delete a record from a table, even if
rows in another table reference the record through a FOREIGN KEY constraint?
a. CASCADE
b. CASCADE ON DELETE
c. DELETE ON CASCADE
d. DROP
e. ON DELETE CASCADE
15. Which of the following data dictionary objects should be used to view information about the
constraints in a database?
a. USER_TABLES
b. USER_RULES
c. USER_COLUMNS
d. USER_CONSTRAINTS
e. None of the above objects should be used.
16. Which of the following types of constraints can’t be created at the table level?
a. NOT NULL
b. PRIMARY KEY
c. CHECK
d. FOREIGN KEY
e. None of the above constraints can be created at th
OR