Master in It
Short Answered Questions:
1. What is the purpose of having foreign key(s) in a relational database table?
i. Represent a relationship between tables ii. Foreign key in one table has the same value, referencing another table’s primary key iii. Referential integrity
2. What is the purpose of having a primary key in the relational database table?
i. Primary key is used as a unique identifier to represent the data in that row. ii. It is also used to provide a link to related tables (by being used as a foreign key). iii. The primary key MUST determine all non-key attributes.
3. How are relationships between tables expressed in a relational database?
i. Use of embedded foreign keys ii. Use of a separate relation table
4. When do you have to use an “intersection entity” and what is it?
“Intersection entity” is an entity used in order to resolve M to M relationships. M-M relationships can be converted to a pair of one to many relationships by creating an intersection entity that contains one occurrence for each related pair. In general it means that a primary key from each entity becomes a part of the composite key for the intersection entity.
5. Briefly explain what would be main advantages of your newly created database system over an existing spreadsheet?
i. Avoids update, insert and delete anomalies ii. Avoids data redundancy iii. Better design structure, security, data independence
6. Database Management Systems contains two main parts in a database: data and meta-data. What is meta-data?
Data only becomes useful when placed in some context. The primary mechanism for providing context for data is meta-data. Mata-data is data about data. It describes the properties or characteristics of other data. Some of these properties include data definitions, data structures and rules or constraints.
7. What is a Database?
A
1. What is the purpose of having foreign key(s) in a relational database table?
i. Represent a relationship between tables ii. Foreign key in one table has the same value, referencing another table’s primary key iii. Referential integrity
2. What is the purpose of having a primary key in the relational database table?
i. Primary key is used as a unique identifier to represent the data in that row. ii. It is also used to provide a link to related tables (by being used as a foreign key). iii. The primary key MUST determine all non-key attributes.
3. How are relationships between tables expressed in a relational database?
i. Use of embedded foreign keys ii. Use of a separate relation table
4. When do you have to use an “intersection entity” and what is it?
“Intersection entity” is an entity used in order to resolve M to M relationships. M-M relationships can be converted to a pair of one to many relationships by creating an intersection entity that contains one occurrence for each related pair. In general it means that a primary key from each entity becomes a part of the composite key for the intersection entity.
5. Briefly explain what would be main advantages of your newly created database system over an existing spreadsheet?
i. Avoids update, insert and delete anomalies ii. Avoids data redundancy iii. Better design structure, security, data independence
6. Database Management Systems contains two main parts in a database: data and meta-data. What is meta-data?
Data only becomes useful when placed in some context. The primary mechanism for providing context for data is meta-data. Mata-data is data about data. It describes the properties or characteristics of other data. Some of these properties include data definitions, data structures and rules or constraints.
7. What is a Database?
A