###### Database-Management-System

October 3, 2023###### JNU PhD CS 2019

October 3, 2023# ER-Model

Question 2 |

Given the basic ER and relational models, which of the following is **INCORRECT**?

An attribute of an entity can have more than one value | |

An attribute of an entity can be composite | |

In a row of a relational table, an attribute can have more than one value | |

In a row of a relational table, an attribute can have exactly one value or a NULL value |

Question 2 Explanation:

Option (A): In ER-model, multivalued attribute of an entity can have more than one value.

Option (B): In ER model, the attribute which can be further broken down into some other attributes is called composite attribute.

Option (C): In Relational model, the intersection of one row and column should contain only one value. So, option (C) is INCORRECT.

Option (D): In Relational model, the intersection of one row and column should contain either exactly one value or NULL.

Option (B): In ER model, the attribute which can be further broken down into some other attributes is called composite attribute.

Option (C): In Relational model, the intersection of one row and column should contain only one value. So, option (C) is INCORRECT.

Option (D): In Relational model, the intersection of one row and column should contain either exactly one value or NULL.

Correct Answer: C

Question 2 Explanation:

Option (A): In ER-model, multivalued attribute of an entity can have more than one value.

Option (B): In ER model, the attribute which can be further broken down into some other attributes is called composite attribute.

Option (C): In Relational model, the intersection of one row and column should contain only one value. So, option (C) is INCORRECT.

Option (D): In Relational model, the intersection of one row and column should contain either exactly one value or NULL.

Option (B): In ER model, the attribute which can be further broken down into some other attributes is called composite attribute.

Option (C): In Relational model, the intersection of one row and column should contain only one value. So, option (C) is INCORRECT.

Option (D): In Relational model, the intersection of one row and column should contain either exactly one value or NULL.

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