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5.	What is a foreign key?
	A foreign key is an attribute in a child table that matches the primary key value in the parent table.
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6.	What is de–normalization?
	OLTP databases are intended more for DML operations; therefore these databases are designed to reduce redundancy; whereas, Online Analytical Processing (OLAP) database or warehousing applications are primarily used for reporting. OLAP databases are not used for day–to-day transactions in general and reporting performance is more critical for such database; therefore, these databases are designed to store data to support easy access without requiring too many joins. Redundancy of data is not of much concern in these databases; therefore, tables are designed as a join of two or more tables from a typical OLTP application. This is called de-normalization.
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7.	What are the components of logical data model?
	Following are the components of the logical data model: Entity – Refers to an object of interest, that is, something that we want to store information about. In a relational database structure, each entity has its own table, that is, a structure of rows and columns. Attribute – Refers to the property or the information of the entity that we are interested in. It is stored as a column of the table and has specific data type associated with it. Record – Refers to a collection of all the properties associated with an entity for one specific condition. it is represented by a row in a table. Tuple – Refers to the design of a record. Domain – Refers to the description of the legitimate values for an attribute. It is the set of all the possible values for that attribute. Relation – Represents a relation between two entities. Therefore, a relation database is a collection of entities and relationships. Relational database – Refers to a set of related entities, which is used to store required information as per the design.
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8.	What is transitive dependency?
	A transitive dependency is the situation when an attribute indirectly depends on another attribute through a third attribute.
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