Answer the following questions
(2 x 10 = 20 marks)
1. Define Primary Key.
2. What is Domain Integrity.
3. Referential integrity ensures that for every value of a foreign key, there is a matching
value of
4. What is Schema?
5. Define Candidate Key.
6. The term is used to refer to a row.
7. Define Data Dictionary.
8. What is weak entity set?
9. What is Clustering?
10. Define OLAP.
Answers
1. A primary key is a unique identifier for a database record. When a table is created, one of the fields is typically assigned as the primary key. While the primary key is often a number, it may also be a text field or other data type.
2. Domain integrity specifies that all columns in a relational database must be declared upon a defined domain. The primary unit of data in the relational data model is the data item. Such data items are said to be non-decomposable or atomic. A domain is a set of values of the same type.
3. A referential integrity constraint requires that for each row of a table, the value in the foreign key matches a value in a parent key. ... It guarantees that every value in this column must match a value in the primary key of the dept table (also the deptno column).
4. A diagrammatic presentation broadly.
5. CANDIDATE KEY is a set of attributes that uniquely identify tuples in a table. Candidate Key is a super key with no repeated attributes. ... Every table must have at least a single candidate key. A table can have multiple candidate keys but only a single primary key.
6. Q The term _______ is used to refer to a row.
Tuple is one entry of the relation with several attributes which are fields.
7. A data dictionary is a collection of the names, definitions, and attributes for data elements and models. The data in a data dictionary is the metadata about the database. These elements are then used as part of a database, research project, or information system.
8. An entity set that does not have a primary key is referred to as a weak entity set. ... A distriminator of a weak entity set is the set of attributes that distinguishes among all the entities of a weak entity set.
9. To form a group, sometimes by surrounding something, or to make something do this: People clustered around the noticeboard to read the exam results.
10. OLAP (for online analytical processing) is software for performing multidimensional analysis at high speeds on large volumes of data from a data warehouse, data mart, or some other unified, centralized data store.