Can weak entity be converted into strong entity?

Answer 1

The primary key of a weak entity set is formed by taking the primary key of the strong entity set on which its existence depends (see Mapping Constraints) plus its discriminator.

A strong entity set has a primary key. All tuples in the set are distinguishable by that key. A weak entity set has no primary key unless attributes of the strong entity set on which it depends are included. Tuples (a particular row) in a weak entity set are partitioned according to their relationship with tuples in a strong entity set. Tuples within each partition are distinguishable by a discriminator, which is a set of attributes.

Answer 2

A weak entity is an entity set that does not have sufficient attributes so that it can form a primary key. A weak entity is depicted by drawing double rectangle in entity relationship diagrams. While a strong entity is an entity set that have sufficient attributes so that it can form a primary key.

Answer 3

1.)Though weak entity set can be converted into strong entity set by simply adding appropriate attributes, this approach results in the redundant storage of primary key.

2.) The primary key of a weak entity set can be inferred from its relationship with the storage entity set.

Answer 4

An entity set that does not possess sufficient attributes to form a primary key is called a weak entity set. One that does have a primary key is called a strong entity set.

The discriminator (or partial key) of a weak entity set is the set of attributes that distinguishes among all the entities of a weak entity set

The existence of a weak entity set depends on the existence of a identifying entity set. It must relate to the identifying entity set via a total, one-to-many relationship set from the identifying to the weak entity set

We depict a weak entity set by double rectangles in E-R diagram. We underline the discriminator of a weak entity set with a dashed line in E-R diagram.

Answer 5

Strong Entity Set:

which entity set does have a primary key is called a strong entity set.

Example:

Set of all Persons,Companies,Trees,Holidays etc.

Weak Entity Set:

which entity set does not have a primary key is known as a weak entity set.

Example:

Specific Person,Company,Event,Plant

MD.ISRAFIL CSE (DHAKA)

Answer 6

Strong entity is an entity set that can uniquely identify a row. Weak entity is an entity set that can not identify a row uniquely. Weak entities are denoted by double rectangle box.