Relational Database Management System
- An RDBMS is a database engine/system based on the relational model specified by Edgar F. Codd.
- Most modern commercial and open-source database applications are relational in nature.
- The most important relational database features include the ability to use tables for data storage while maintaining and enforcing certain data relationships.
Basics of RDBMS
- Domain is a set of atomic values.
- By atomic we mean that each value in the domain is indivisible as far as the formal relational model is concerned.
- A common method of specifying a domain is to specify a data type from which the data forming the domain are drawn.
- Table(Relation): A relation is a set of tupes/rows/entities/records.
- Tuple: Each row of a relation/table is called tuple.
- Degree: Number of columns/attributes of a relation.
- Cardinality: Number of rows/tupes/record of a relational instance.
Properties of RDBMS
- Cells contains atomic values.
- Values in a column are of the same kind.
- Each row is unique.
- Each column has a unique name
- No two tables can have the same name in a relational schema.
- The sequence of rows is insignificant.
- The sequence of columns is insignificant.
Problems in RDMS
- Update anomalies: Anomalies that cause redundant work to be done during insertion into and modification of a relationship and that may cause accidental loss of information during a deletion from a relation.
- Insertion anomalies: An independent piece of information cannot be recorded into a relationship unless an irrelevant must be inserted together at the same time.
- Modification anomalies: The update of a piece of information must occur at multiple locations.
Deletion anomalies: The deletion of a piece of information unintentionally removes other information.
- Normalization may be simply defined as a refinement process.
- It includes creating tables and establishing relationships between those tables according to rules designed both to protect data and make the database more flexible by eliminating two factors:
- Inconsistent dependency.
- Without normalization database systems be inaccurate, slow, and inefficient and they might not produce the data we expect.
The full form of RDBMS is?
Which of the following is the property of transaction that protects data from system failure?
Which of the following is preserved in the execution of transactions in isolation?
Which is the lowest level of abstraction that describes how the data are actually stored?
What is a relation in RDBMS?
“RDBMS has ACID properties”-Which of the following options is true about this statement?
During transaction before commit which of the following statement is done automatically in case of shutdown?
A relational database developer refers to a record as?
The database is always expected to satisfy which predicate?
Which of the following can replace the below query?
SELECT name, course_id FROM instructor, teaches WHERE instructor_ID= teaches_ID;
The database system catalog stores what kind of information?
The local variables that hold write operations are copied to the database work in which phase?
What does the following query do?
UPDATE student SET marks = marks * 1.20;
The relational model of RDBMS is concerned with?
The attribute which is the primary key should have its values never?
The referential integrity constraint of a relational database can be specified with the help of?
Minimal Superkeys are also called?
Which of the following are applications of dynamic hashing?
How can we delete entries in an RDBMS?
Select the correct foreign key constraint?
What is the name of the query that is placed within a WHERE or HAVING clause of another query?
Modify operation is done after which operation?
Date when inserted into a database should be of the format?
Total view of a database is known as?
To select some particular columns, which of the following columns is used?
What is NTFS?
Which of the following are properties of entities?
Which of the following constraints does RDBMS checks before creating tables?
When is a domain called atomic?
Set of one or more attributes taken collectively to uniquely identify a record is called?
Language through which user requests data from a database is called?
The union operation performs the set union of 2 ‘_______’ tables.
The Select command is a part of what type of statement?
What kind of updates are not allowed in RDBMS?
The number of attributes in a relation is called its?
What kind of Joins is a default in SQL?
The primary key must be?
Which of the following are examples of aggregate functions in SQL?
SQL update statements that can only be used in the set clause are called?
Which conditions allows a general predicate over the relations being joined?
What is the maximum number of tables which can be joined with a join?
How can we make a transaction permanent in the database?
Maximum number of children of a B-tree of order N is?
How is the ranking of queries done?
What is the AS clause used for?
OLAP stands for?
What type of data can be modeled as dimensional and measure attributes?
Cross tabs in SQL are created using?