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In a relation we have number of tuple R ={t1,t2,t3.....tn}, nd they follow integrity constraints nd each tuple has a primary key pk.if any of the d two tuple have same attribute. for instance t1=t2 then its pk wud be same too.. but this violates the key constraint..
hence duplicacy not allowed in tuple...
enjoy
Rijo Rajan
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Why duplicate tuples are not allowed in DBMS?
Since relation is a set, and tuples are element of a set, according to set theory, the elements of a set are not ordered.
Why do duplicate tuples not allowed in a reaction?
Duplicate tuples are not allowed in a reaction because each reactant and product must be listed only once to accurately represent the stoichiometry of the reaction. Including duplicate tuples would result in an incorrect representation of the reactants and products involved, leading to inaccuracies in the reaction equation.
02. Why are duplicate tuples not allowed in a relation?
Duplicate tuples are not allowed in a relation to maintain the integrity and uniqueness of the data. Each tuple in a relational database represents a unique record, and allowing duplicates could lead to ambiguity and inconsistency in data retrieval and updates. Enforcing uniqueness helps ensure that each entry can be distinctly identified, which is essential for effective data management and querying. Additionally, it aligns with the mathematical foundation of relations in set theory, where a set cannot contain duplicate elements.
2. Why are duplicate tuples not allowed in a relation?
Duplicate tuples are not allowed in a relation to ensure the integrity and uniqueness of the data. In a relational database, each tuple (or row) represents a unique entity or record, and allowing duplicates would create ambiguity and inconsistencies in data retrieval and manipulation. This principle also supports efficient indexing and searching, as unique identifiers like primary keys can be used to distinguish records. Overall, preventing duplicates helps maintain the relational model's foundational rules and enhances data reliability.
Characteristics of relations in relational database model?
No Duplicate Tuples - A relation cannot contain two or more tuples which have the same values for all the attributes. i.e., In any relation, every row is unique. • Tuples are unordered - The order of rows in a relation is immaterial. • Attributes are unordered - The order of columns in a relation is immaterial. • Attribute Values are Atomic - Each tuple contains exactly one value for each attribute. It may be noted that many of the properties of relations follow the fact that the body of a relation is a mathematical set.
Why are tuples in a relation not ordered?
A relation is defined as a set of tuples. Mathematically, elements of a set have no order among them; hence, tuples in a relation do not have any particular order. In other words, a relation is not sensitive to the ordering of tuples. Tuple ordering is not part of a relation definition because a relation attempts to represent facts at a logical or abstract level. Many logical orders can be specified on a relation but there is no preference for one logical ordering over another.
Why the tuples in a relation are not ordered?
A relation is defined as a set of tuples. Mathematically, elements of a set have no order among them; hence, tuples in a relation do not have any particular order. In other words, a relation is not sensitive to the ordering of tuples. Tuple ordering is not part of a relation definition because a relation attempts to represent facts at a logical or abstract level. Many logical orders can be specified on a relation but there is no preference for one logical ordering over another.
Why does SQL allow duplicate tuples?
There are many reasons why SQL allows duplicate tuples (rows):To store non-unique values.To simply remove primary keys, unique indexes, and unique constraints.It allows this if there is no unique constraint.
What do extension and intentions of relations mean in dbms?
ExtensionThe extension of a given relation is the set of tuples appearing in that relation at any given instance. The extension thus varies with time. It changes as tuples are created, destroyed, and updated.
Entity integrity constraint?
The entity integrity constraint states that no primary key value can be null. This is because the primary key value is used to identify individual tuples in a relation. Having null value for the primary key implies that we cannot identify some tuples. This also specifies that there may not be any duplicate entries in primary key column key row.
How do you calculate number of tuples?
To calculate the number of tuples in a relation (or table) in a database, you need to count the total rows present in that relation. Each row represents a tuple, which contains values for each attribute defined in the relation's schema. You can use a SQL query like SELECT COUNT(*) FROM table_name; to retrieve this count directly from the database. Alternatively, you can manually count the rows if the data is presented in a readable format.
What are the relationships that the relational database is named for?
In database theory, a relation is defined as a set of tuples that have the same attributes. A tuple is also known as a row or record.
