What is a Database?
A database is an organized collection of data, general stores, and accessed electronically from a computer system.
What is DBMS?
The Database Management System(DBMS) is the software that interacts with end-users, applications, and the database itself to capture and analyze the data.
The DBMS software additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS, and the associated applications can be referred to as a “database system”. Check out the frequently asked interview questions on DBMS.
Problems with File System
- Data redundancy and inconsistency.
- Difficulty in accessing data
- Data isolation
- Integrity problem
- Atomicity problem
- Concurrent access anomalies
Instance and Schemas
- The collection of information stored in the database at a particular moment is called an instance of the database.
- The overall design of the database is called the database schema.
Types of Databases
- Commercial database
- Multimedia database
- Deductive database
- Temporal database
- Geological Info System
Characteristics of Database Management System
- Provides security and removes redundancy
- Self-describing nature of a database system
- Insulation between programs and data abstraction
- Support of multiple views of the data
- Sharing of data and multiuser transaction processing
- Database Management Software allows entities and relations among them to form tables.
- It follows the ACID concept ( Atomicity, Consistency, Isolation, and Durability).
What is Transaction?
- To remove this partial execution problem, we increase the level of atomicity and bundle all the instructions of a logical operation into a unit called a transaction.
- So, formally - ‘A transaction is a set of logically related instructions to perform a logical unit of work’.
What is a Schedule?
- When two or more transactions are executed together or one after another, then they can be bundled up into a higher unit of execution called schedule.
- A schedule of N transactions T1, T2, T3...TN, is an ordering of the operations of the transactions. Operations from different transactions can be interleaved in the scheduled S.
- However, the schedule for a set of transactions must contain all the instructions of those transactions, and for each transaction T, that participates in the schedule S, the operation of T, in S must appear in the same order in which they occur in T.
Basics of RDBMS
- The 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 a tuple.
- Degree: Number of columns/attributes of a relation.
- Cardinality: Number of rows/types/record of a relational instance.
Properties of RDBMS
- Cells contain 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.
Useful Resources
- Database Testing
- Difference between RDBMS and DBMS
- Complete Technical Interview Guide
- Complete DBMS Tutorial by Scaler
DBMS MCQ Questions
Which of the following command is used to change data in table?
Real-Life Problems
Prep for Target Roles
Custom Plan Duration
Flexible Plans
What is rows of a relation known as?
What is the name of the query that is placed within a WHERE or HAVING clause of another query?
What is the number of tuples of a relation known as?
What is the use of COUNT in SQL?
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Which command is used to remove a stored function from the database?
Which data structure is used in Hierarchical model records?
Real-Life Problems
Detailed reports
Which is AS clause used for?
Which is the lowest level of abstraction that describes how the data are actually stored?
Which normal form deals with multivalued dependency?
Which normalization form is based on the transitive dependency?
Which of the following allows to uniquely identify a tuple?
Which of the following can replace the below query?
SELECT name, course_id
FROM instructor, teaches
WHERE instructor_ID= teaches_ID;
What is DBMS?
Which of the following is a command of DDL?
Which of the following is known as minimal super key?
Which of the following is not a SQL command?
Which of the following is preserved in execution of transaction in isolation?
Which of the following is the full form of DDL?
Which of the following is the full form of NTFS?
Which of the following is the full form of TCL?
Which of the following is the property of transaction that protects data from system failure?
Which of the following normal forms contains information about a single entity?
Which of the following operator is used to compare a value to a list of literals values that have been specified?
Which of the following SQL command is used for removing (or deleting) a relation form the database?
Select the correct command to modify a column in a table.
After which operation is the modify operation done?
During transaction before commit which of the following statement is done automatically in case of shutdown?
For performing tasks like creating the structure of the relations, deleting relation, which of the following is used?
How is ER diagram represented?
How many levels are there in architecture of database?
Identify the concurrency based protocol?
Maximum children of a B-tree of order m?
NATURAL JOIN can also be termed as -
Primary key can be?
Rectangles in ER diagram represents?
Select the correct advantages of view.
Select the correct command to find the number of values in a column.
A relational database developer refers to a record as?
Select the correct database object which does not exist physically.
Select the correct definition of relation.
Select the correct definition of Relational calculus?
Select the correct foreign key constraint?
Select the correct properties of entities?
Select the definition of the correct key which is used to represent relation between two tables?
Select the relational algebra operations.
Select the valid SQL type.
To select some particular columns, which of the following command is used?
Total view of a database is known as?
What is a table joined with itself called?
