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What is a non key attribute in normalization?
A non-key attribute is an attribute in a relation that is not part of the primary key. These attributes are functionally dependent on the primary key and are subject to normalization to reduce data redundancy and improve database consistency.
Discuss the difference between a composite key and a composite attribute.How would each be indicated in an ERD?
Attribute is the property of entity.The composite attribute is like address(where street no,house no,town name all include).Composite key is also an attribute,but only which attribute are work as a unique identifier. Example:> In an ERD if vendor placed with orders then order(order day, order number) vendor(vendor code,vendor address) Here, order and vendor both are entity and order number, vendor code both are Composite key(because those are unique)but vendor address is a Composite attribute and order day(may be not unique)is an attribute only. So, we can conclude that all attribute not Composite key.
What is data dependency in DBMS?
Data dependency in DBMS refers to the relationship between different data elements within a database. There are three main types: functional dependency (one attribute determines another), partial dependency (part of a composite key determines other attributes), and transitive dependency (dependency between non-key attributes). Understanding data dependencies is crucial for database normalization and maintaining data integrity.
What is second normal form in DBMS?
Second normal form (2NF) in DBMS states that a table is in 2NF if it is in 1NF and all attributes that are not part of the primary key are fully functionally dependent on the whole primary key. This means that each non-key attribute is fully dependent on the primary key, and not on a subset of the key.
Which is an attribute?
An attribute is a characteristic or feature of an object or entity. It helps to describe or define the object by providing specific information about it. Examples of attributes include color, size, shape, and weight.
What is a non key attribute in normalization?
A non-key attribute is an attribute in a relation that is not part of the primary key. These attributes are functionally dependent on the primary key and are subject to normalization to reduce data redundancy and improve database consistency.
What are key attribute and non key attribute?
Attributes can be classified as identifiers or descriptors. Identifiers, more commonly called keys or key attributes uniquely identify an instance of an entity. If such an attribute doesn't exist naturally, a new attribute is defined for that purpose, for example an ID number or code. A descriptor describes a non-unique characteristic of an entity instance. An entity usually has an attribute whose values are distinct for each individual entity. This attribute uniquely identifies the individual entity. Such an attribute is called a key attribute. For example, in the Employee entity type, EmpNo is the key attribute since no two employees can have same employee number. Similarly, for Product entity type, ProdId is the key attribute. There may be a case when one single attribute is not sufficient to identify entities. Then a combination of attributes can solve this purpose. We can form a group of more than one attribute and use this combination as a key attribute. That is known as a composite key attribute. When identifying attributes of entities, identifying key attribute is very important.
What are the requirements for a relation to be in Second Normal Form?
A relation is in second normal form (2NF) if any of the following conditions apply: The primary key consists of only one attribute No non-primary key attribute exists in the relation Every non-primary key attribute is functionally dependent on the full set of primary key attributes
Non-prime attribute in DBMS?
Prime attribute are part of any candidate key. Non-prime attribute are not part of any candidate key.
Is foreign key a non key attribute?
a key to a different table
What is key attribute and entity in database?
The attribute (or combination of attributes) that is unique for every entity instance e.g.: the account number of an account, the employee id of an employee etc.
What is difference between primary key and foreign key?
A primary key is an attribute (or combination of attributes) that uniquely identifies each row in a relation. A primary key is designated by underlining the attribute name. The primary key of an entity set allows us to distinguish among the various entities of the set. A foreign key is an attribute in a relation of database that serves as the primary key of another relation in the same database.
Explain different types of attributes with example in DBMS.?
Different types of attributes in DBMS are:Key or non key attributesRequired or optional AttributesSimple or composite AttributesSingle-valued and multi-valued AttributesStored, Coded or derived Attributes
What is the prime attribute in DBMS?
prime attributes are the attributes of a candidate key which will give uniqueness. a candidate key is (the subset of superkey) which gives uniqueness. Super key is the maximum set of attributes that can provide uniqueness example ABCDE is a super key AB CD DE are the candidate keys s.t. AB is the primary key. CD and DE are the secondary/alternate keys.
Can you sort a table without a primary key?
Yes. You can sort on any attribute or combination of attributes in a table (in SQL using the "order by" clause). Of course the sort is only as good as the "uniqueness" of the attribute you sort on, hence a combination of attributes may be helpful. A primary key is, by definition, unique across all rows in the table.
What part of speech is attributes?
Attributes is a noun (plural form of attribute) and a verb (third person singular conjugation of attribute).
What is the antonym for the word attributes?
Giving an antonym for the word attributes can be tricky, mainly because of its meaning, as in, giving credit to or being an aspect of something. Giving an opposite of, "attributed the painting to Titian;" (WikiAnswers) could be reverted as a non-attribute.
