10 Questions
What is a superkey in the context of relational databases?
A set of all attributes in a relation that specifies no two tuples can have the same value
What is the purpose of the entity integrity constraints in relational databases?
To specify that no primary key value can be null
What is the function of the select operation in relational algebra?
Selecting tuples that satisfy a given predicate
What is the DEGREE OF A RELATION?
The total number of attributes in a relation schema
Which type of constraint is DOMAIN CONSTRAINTS?
Schema-based constraints
What is the purpose of KEY CONSTRAINTS?
To ensure that each tuple in a relation is unique
What does SQL stand for?
Structured Query Language
Which SQL component is used to modify database schema?
DDL
What is the purpose of Cartesian product in SQL?
Combining information of two different relations into one relation
Which SQL keyword is used to delete data from a database?
DELETE
Study Notes
Relational Databases
- A superkey is a set of attributes that uniquely identifies a tuple in a relation.
- Entity integrity constraints ensure that each tuple in a relation has a unique value for the primary key.
Relational Algebra
- The select operation is used to select a subset of tuples from a relation that satisfies a given condition.
Relations
- The degree of a relation is the number of attributes in a relation.
Constraints
- Domain constraints are constraints that apply to a single attribute or column of a relation, restricting the set of values it can take.
- Key constraints are used to ensure that each tuple in a relation has a unique value for the primary key.
SQL
- SQL stands for Structured Query Language.
- The DDL (Data Definition Language) component of SQL is used to modify the database schema.
- The Cartesian product operation in SQL is used to combine each row of one relation with each row of another relation.
- The DELETE keyword is used to delete data from a database.
Test your knowledge on relation attributes, degrees of a relation, cardinality, and relational model constraints with this quiz. Learn about defining relation schemas, counting attributes, and understanding the total number of tuples in a relation. Explore the concept of constraints in relational models.
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