relationship type,degree, cardinality, optionality terms confusion

Question

I currently studying database i've seen degree and cardinality uses as same term, or in some other degree is defined as no. of entities involved in a relationship and further catogories as unary, binary and trenary.

Some placed degree is defined as The degree of a relationship type concerns the number of entities within each entity type that can be linked by a given relationship type.

Cardinality is minimum and maximun number of entity occurrence associated with one occurrence of the related entity

cardinality types as 1 to 1 , 1 to many , many to many. or min and max cardinality.

Min degree is optionality and maximum degree is cardinalty.

what is the difference between degree and cardinaltiy ?

In another context cardinality is a number of rows in table and degree is a number of columns.

So what i'm i suppose to write if question is asked "Define cardinality ?".

Can somebody explain ?

Answer 1

Degree - number of attributes (columns) in a relation (table)

Cardinality - number of tuples (rows) present in a table

See this for more details.

Answer 2

Ok here is the explanation

1.Degree. This is the number of entities involved in the relationship and it is usually 2 (binary relationship) however Unary and higher degree relationships can be exists.

2.Cardinality. This specifies the number of each entity that is involved in the relationship there are 3 types of cardinality for binary relationships

• one to one (1:1)
• one to many (1:n)
• many to many (n:m)

hope this will clear your mind. Please communicate for more information