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30. Which of the following enforces a database constraint?
a. PRIMARY KEY b. UNIQUE c. FOREIGN KEY d. All of these
31. Which statement can be used to select employees from the EMPLOYEE table whose name begins with K?
a. SELECT * FROM EMPLOYEE WHERE name LIKE '%K';
b. SELECT * FROM EMPLOYEE WHERE name LIKE '%K%';
c. SELECT * FROM EMPLOYEE WHERE name LIKE '_K%';
d. SELECT * FROM EMPLOYEE WHERE name LIKE 'K%';
32. Which statement can be used to select employees from the EMPLOYEE table whose name ends with Narayanan?
a. SELECT * FROM EMPLOYEE WHERE name LIKE '%Narayanan';
b. SELECT * FROM EMPLOYEE WHERE name LIKE '%Narayanan%';
c. SELECT * FROM EMPLOYEE WHERE name LIKE '%_Narayanan%';
d. SELECT * FROM EMPLOYEE WHERE name LIKE 'Narayanan';
33. Which statement can be used to select employees from the EMPLOYEE table whose name contains Kumar?
a. SELECT * FROM EMPLOYEE WHERE name LIKE '%Narayanan';
b. SELECT * FROM EMPLOYEE WHERE name LIKE '%Kumar%';
c. SELECT * FROM EMPLOYEE WHERE name LIKE '_K%';
d. SELECT * FROM EMPLOYEE WHERE name LIKE 'K%';
34. Which SQL statement is used to display the result of a query in ascending order of a particular attribute?
a. ORDER BY b. SORT BY c. ORDER d. SORT
35. Which of the following aggregate functions ignores NULL values?
a. COUNT() b. SUM() c. MIN() d. All of these
B. State whether the following statements are True or False:
1. One row of a table stores information about all attributes of an entity. _________
2. A database administrator is a person who manages the entire database by controlling access of
hardware and software resources. _________
3. A key always refers to a single attribute that uniquely identifies a tuple. _________
4. A failed insert operation does not change the database state. _________
5. An end-user decides which components of the database he/she will access. _________
6. DBMS may allow a user to access the salary of the employees in the EMPLOYEE table, but may
not allow access to the Addresses of the employees. _________
7. DBMS does not ignore the ordering of tuples in a relation. _________
8. A DDL command can be used to modify the constraints of an attribute in a table. _________
9. A DML command can only be used to retrieve data. _________
10. A string longer than the defined maximum length will result in the truncation of extra trailing
characters. _________
11. A VARCHAR data type can have a default value. _________
12. A table may have more than one attribute as a primary key. _________
13. SELECT is a DDL command. _________
14. UNIQUE constraint can be applied to multiple columns in a table. _________
C. Fill in the blanks.
1. Each column of a table represents a unique ______________.
2. ______________ describes the structure of a relation.
3. The number of attributes in a relation is known as ______________ of a relation.
4. A set of all tuples in a relation is known as ______________.
5. When a key in a table has got more than one attribute, it is known as ______________.
270 Touchpad Informatics Practices-XI

