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15. Which of the following statements are true?
a. There can be only one key with unique values in table b. There can be only one primary key in a table.
c. There can be only one foreign key in a table. d. A table must have a primary key.
16. Which of the following is used to ensure that an attribute is not left unspecified?
a. BLANK b. NOT NULL c. DISTINCT d. UNIQUE
17. Which of the following is the keyword used in SELECT query to avoid duplicate records?
a. UNIQUE b. DISTINCT c. PRIMARY KEY d. DIFFERENT
18. The HAVING keyword is used with ________ clause.
a. ORDER BY b. SORT BY c. GROUP BY d. UPDATE
19. Which of the following functions returns the average value of an SQL expression?
a. AVG() b. AVERAGE() c. MEAN() d. AVERAGEVALUE()
20. Which SQL data type is most suitable for storing date of birth values of the students?
a. CHAR b. VARCHAR c. DATE d. INTEGER
21. Which of the following is a DML statement?
a. ALTER b. CREATE c. DELETE d. None of these
22. What is the correct expansion of DDL?
a. Dual Data Language b. Data Decision Language
c. Data Definition Language d. Data Development Language
23. Which of the following statements is NOT true with respect to databases?
a. DML is used for retrieval of data. b. DML is used for modification of data.
c. DDL is used for specifying constraints. d. DDL is used to delete a row from a database.
24. Which of the following is not a VALID integer value?
a. –5656 b. –5,65,656 c. –0 d. –5656.65
25. While creating a table, Rachita does not want the field value of attribute Hobby to be left blank. Instead, she wants the
value "NOT AVAILABLE" to be stored. Which of the following constraints should she use while defining the Hobby field
during the creation of the table?
a. CHECK b. DEFAULT c. UNIQUE d. NOT NULL
26. Which of the following statements will display the structure of the table, PRACTICE?
a. DESC PRACTICE b. STRUCTURE PRACTICE
c. SHOW PRACTICE d. DISPLAY PRACTICE
27. If an attribute Title is created with the following specifications:
Title CHAR(10) NOT NULL
Which of the following statements is NOT correct?
a. Title will be allocated 10 bytes of memory in all cases.
b. Title will be allocated memory according to the length of the field value, but maximum will be 10 bytes.
c. If an attempt is made to insert a string of length more than 10 characters, an error will be generated.
d. If the field value is less than 10 characters, the remaining characters will be filled by blanks.
28. Which operator is used to check whether an attribute is NULL values in SQL?
a. IS b. = c. EQUAL d. IN
29. Which of the following is the correct order of clauses in a SELECT statement?
a. SELECT, WHERE, ORDER BY, GROUP BY
b. SELECT, WHERE, GROUP BY, HAVING
c. SELECT, WHERE, ORDER BY, HAVING
d. SELECT, WHERE, HAVING, GROUP BY
Database Concepts and the Structured Query Language 269

