Preparing for BIT – IT2301 Database Management Systems, on Rupavahini, 09th August 2001, 2200-2230 hrs & 20th August 2001, 1600-1630 hrs.

1. IT2301 Database Management Systems [email_address] PREPARING FOR THE BIT Preparing for BIT 09/08/2001

2. Instructions for providing answers Use black or blue ink ball point pens OR. Use a good quality HB2 pencil . Announcements b a c d  e 

3. Exam Admission Cards and Model Papers were posted. Few Corrections were made to some model papers and the corrections published on the web. There were OS questions using C , these would be changed to Java . Students need not know C as a programming language for this module Announcements

4. IT2301 Model Question Paper Last Time (Q) 9-18 Today (Q) 19-25

5. 19) Which of the following characteristic(s) is (are) not suitable for use as the primary key of an employee? (a) Employee identity no. (b) Date of birth (c) Address of employee (d) Full name of employee (e) Photograph of employee

6. Primary Key Uniqueness property, Fixed Length, Small in size if used to link tables (a) Employee identity no. (b) Date of birth (c) Address of employee (d) Full name of employee (e) Photograph of employee

7. 20) Which of the following statement(s) is (are) true with respect to data types ? (a) FLOAT data type can store twice as many digits as SMALLFLOAT. (b) INTEGER data type can store decimal numbers exceeding that number 32,767 (c) VARCHAR data type often reduces disk storage wastage when compared to CHAR data type. (d) BLOB data is streams of bytes of fixed length. (e) BYTE data type cannot store any type of binary data.

8. Data Types (a) FLOAT data type can store twice as many digits as SMALLFLOAT. Refers to Precision and Not Large in Number FLOAT (DOUBLE PRECISION) Double Precision 14-16 significant digits SMALLFLOAT (REAL) Single Precision 7-8 significant digits

9. Data Types (b) INTEGER data type can store decimal numbers exceeding that number 32,767 INTEGER can store whole numbers Not Decimals

10. Data Types (c) VARCHAR data type often reduces disk storage wastage when compared to CHAR data type. CHAR fixed length of specified value VARCHAR variable length up to specified maximum

11. Data Types (d) BLOB data is streams of bytes of fixed length. Binary Large Object (BLOB) is a streams of bytes of arbitrary value and length. A BLOB might be a digitised image or sound

12. Data Types (e) BYTE data type cannot store any type of binary data. BYTE is a type of BLOB Stores non-character-based information such as digitised images, sound Therefore, can store binary data.

13. 21) Which of the following may happen during the process of normalization ? (a) creation of new tables, (b) splitting of a table into several tables, (c) merging of several tables into one table, (d) removing some relationships among existing relations of the scheme, (e) removing existing constraints.

14. Normalisation (a) creation of new tables functional dependencies on part of key and transitive dependencies are removed by putting these attributes in separate tables. Thus we create new tables. As well as split existing tables. (b) splitting of a table into several tables

15. Normalisation (c) merging of several tables into one table merging of tables is required only to denormalised relations (d) removing some relationships among existing relations of the scheme, (e) removing existing constraints last two options has nothing to do with normalisation process.

16. 22) Which set of operators represent the complete set for relational algebra ? (a) Union, Difference, Projection, Selection, Cartesian Product (b) Selection, Cartesian Product, Projection, Union, Intersection (c) Cartesian Product, Projection, Selection, Difference, Intersection (d) Join, Union, Projection, Selection, Difference (e) Difference, Projection, Selection, Join, Intersection

17. Relational Algebra Set Operators Union, Difference (Minus), Intersection Relational Operators Projection, Selection (Restrict), Cartesian Product, Join, Natural Join, Divide The complete set is sufficient to reconstruct any other operator. E.g. Intersection, Join etc may be reconstructed using this set. (a) Union, Difference, Projection, Selection, Cartesian Product

18. 23) Which of the following are supported by Entry-level SQL-92 standard ? (a) Embedded SQL (b) Integrity enhancement (c) System catalogs (d) Triggers and stored procedures (e) Outer Join

25. 24) Which set of key words cannot be used with SQL INSERT statement to enter data? (a) Insert, Select, Into, Set, Where (b) Insert, Into, Values, Copy (c) Select, Into, From, Where, Having (d) Into, Insert, Values, Null (e) From, Distinct, To, Insert, Having

27. 25) Select the statement(s) that is (are) correct with respect to the use of JOIN (a) A table can join to itself creating a self-referencing join called a SELF-JOIN. (b) An EQUI-JOIN between two tables in a SELECT statement returns only the rows that have matching values in the join columns. (c) In an OUTER-JOIN, all of the rows of the dominant table are retrieved regardless of whether there are corresponding rows in the other table. (d) In an OUTER-JOIN, a join condition does not need to have the WHERE clause. (e) OUTER-JOIN cannot be used to join 3 tables.

28. JOIN (a) A table can join to itself creating a self-referencing join called a SELF-JOIN. Employee( empno , name, supervisor, deptno) SELECT e.empno, e.name, s.name FROM Employee e, Employee s WHERE e.empno=s.supervisor

29. JOIN (b) An EQUI-JOIN between two tables in a SELECT statement returns only the rows that have matching values in the join columns. Employee( empno , name, supervisor, deptno) Department( deptno , name) SELECT e.empno, e.name, d.name FROM Employee e, Department d WHERE e.deptno=d.deptno

30. JOIN (c) In an OUTER-JOIN, all of the rows of the dominant table are retrieved regardless of whether there are corresponding rows in the other table. SELECT e.empno, e.name, d.name FROM Employee e, OUTER JOIN Department d WHERE e.deptno=d.deptno Retrieve all employee data regardless of match. Use NULL for those not matched.

31. JOIN (d) In an OUTER-JOIN, a join condition does not need to have the WHERE clause. SELECT e.empno, e.name, d.name FROM Employee e, OUTER JOIN Department d WHERE e.deptno=d.deptno OR SELECT e.empno, e.name, d.name FROM (Employee AS e OUTER JOIN Department AS d ON e.deptno=d.deptno)

32. JOIN (e) OUTER-JOIN cannot be used to join 3 tables.