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.
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Deletion anomalies: The deletion of a piece of information unintentionally removes other information.
Normalization
- 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:
- Redundancy
- Inconsistent dependency.
- Without normalization database systems are inaccurate, slow, and inefficient and they might not produce the data we expect.
Additional Resources
RDBMS MCQs
What type of data can be modeled as dimensional and measure attributes?
Real-Life Problems
Prep for Target Roles
Custom Plan Duration
Flexible Plans
The Select command is a part of what type of statement?
The union operation performs the set union of 2 ‘_______’ tables.
To select some particular columns, which of the following columns is used?
Total view of a database is known as?
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What does the following query do?
UPDATE student
SET marks = marks * 1.20;What is a relation in RDBMS?
Real-Life Problems
Detailed reports
What is NTFS?
What is the AS clause used for?
What is the maximum number of tables which can be joined with a join?
What is the name of the query that is placed within a WHERE or HAVING clause of another query?
What kind of Joins is a default in SQL?
What kind of updates are not allowed in RDBMS?
The relational model of RDBMS is concerned with?
When is a domain called atomic?
Which conditions allows a general predicate over the relations being joined?
Which is the lowest level of abstraction that describes how the data are actually stored?
Which of the following are applications of dynamic hashing?
Which of the following are examples of aggregate functions in SQL?
Which of the following are properties of entities?
Which of the following can replace the below query?
SELECT name, course_id
FROM instructor, teaches
WHERE instructor_ID= teaches_ID;Which of the following constraints does RDBMS checks before creating tables?
Which of the following is preserved in the execution of transactions in isolation?
Which of the following is the property of transaction that protects data from system failure?
“RDBMS has ACID properties”-Which of the following options is true about this statement?
Select the correct foreign key constraint?
Cross tabs in SQL are created using?
Date when inserted into a database should be of the format?
During transaction before commit which of the following statement is done automatically in case of shutdown?
How can we delete entries in an RDBMS?
How can we make a transaction permanent in the database?
How is the ranking of queries done?
Language through which user requests data from a database is called?
Maximum number of children of a B-tree of order N is?
Minimal Superkeys are also called?
Modify operation is done after which operation?
OLAP stands for?
A relational database developer refers to a record as?
Set of one or more attributes taken collectively to uniquely identify a record is called?
SQL update statements that can only be used in the set clause are called?
The attribute which is the primary key should have its values never?
The database is always expected to satisfy which predicate?
The database system catalog stores what kind of information?
The full form of RDBMS is?
The local variables that hold write operations are copied to the database work in which phase?
The number of attributes in a relation is called its?
The part of database design linked to the logical design is?
The primary key must be?
The referential integrity constraint of a relational database can be specified with the help of?
