CS403 Midterm Solved Subjective with References by Moaaz

Solved Subjective · From Midterm Papers · May 04,2012 · PSMD01 · Fall 2011

Q1. Write the two types of Completeness Constrains? (2 marks)

Answer: (Page 103) There are two types of completeness constraints, partial completeness constraints and total completeness constraints.

Q2. Define main functionality of subtype discriminator? (2 marks)

Answer: (Page 108) This is a tool or a technique which provides us a methodology to determine that to which subtype one instance of a supertype belongs.

Q3. If we have two entities make it one to one relationship? (2 marks)

Q4. what is difference between relation and relationship 2 marks (2 marks)

Relationship is purely a construct of the er data model. Relation is a structure of the relational data model.

Q5. If we map a unary relationship into relationship and ERD has one to one cardinality then what would be the mapping producer? (3 marks)

Answer: (Page 89)

Q6. Make relation b/w two tables with foreign key? With example. (3 marks)

Answer: (Page 133) EMP (empId, empName, qual, depId) DEPT (depId, depName, numEmp) In this example there are two relations; EMP is having record of employees, whereas DEPT is having record of different departments of an organization. Now in EMP the primary key is empId, whereas in DEPT the primary key is depId. The depId which is primary key of DEPT is also present in EMP so this is a foreign key.

What do you know about the cardinalities of relationship? (2 Marks)

Answer: (Page 89) The cardinality of a relationship is the number of entities to which another entity can map under that relationship.

Answer: (Page 197) In Microsoft SQL Server™, each column, local variable, expression, and parameter has a related data type, which is an attribute that specifies the type of data (integer, character, money, and so on) that the object can hold.

How to implement one-to-one relationship while designing tables? (3 Marks)

Answer: (Page 143) In this relationship primary key of one entity type has to be included on other as foreign key. One-to-Many relationships are implemented by splitting the data into two tables with primary key and foreign key relationships.

Name the three different kinds of anomalies which can be eliminated through normalization? (3 Marks)

Answer: (Page 170)

• Insertion Anomaly
• Deletion Anomaly
• Updating Anomaly

Shortly describe procedural DML and Non-procedural DML. Also give their alternate names. (5 Marks)

Answer: (Page 208) There are two types of DML. First is procedural in which: the user specifies what data is needed and how to get it. Second is nonprocedural in which the user only specifies what data is needed.

What is a functional dependency F said to be minimal? (5 Marks)......

Answer: (Page 165) A minimal super key is the candidate key , so if a determinant of functional dependency determines all attributes of that relation then it is definitely a super key and if there is no other functional dependency

Q21. what do you know about partial dependency? (2)

A partial dependency is a dependency where A is functionally dependant on B (A → B), but there is some attribute on A that can be removed from A and yet the dependacy stills holds.

Q22. Define domain of an attribute? (2)

Answer: (Page 75) Domain is the set of possible values that an attribute can have, that is, we specify a set of values either in the form of a range or some discrete values, and then attribute can have value out of those values.

Q23. Define relationship type? (3)

Answer: (Page 85) A relationship type is an abstraction of a relationship i.e. a set of relationships instances sharing common attributes.

Q24. Describe shortly “the difference Operation “in relational algebra? (3)

Answer: (Page 154) If R and S are two relations which are union compatible then difference of these two relations will be set of tuples that appear in R but do not appear in S. It is denoted by (-).

Q25. Explain the salient features of foreign key with help of example? (5)

A foreign key is a mechanism in a relational database that allows for the association of those tables, or for the tables to have a relationship with one another. There are unique characteristics that a foreign key must have.

A foreign key guarantees that rows in one table correspond to rows in some other table, thereby establishing database-wide relationships, or references. The table containing the foreign key is the "child," and the other table is the "parent."