DBMS Interview Questions and Answers
What is DBMS?
A database management system (DBMS) is system software. The DBMS is used for creating databases and manipulating data and records in an organized way.
What is RDBMS?
RDBMS stands for Relational Database Management System. it is based on relational blocks. RDBMS replaces the traditional file system to store the data. All modern systems follow the concept of RDBMS. for example MS SQL Server, Oracle, MySQL etc.
What is Relational Database?
A relational database is a collection of tables and the tables are related to each other. Data is organized in the form of a matrix of rows and columns. The columns are Fields and Rows are the records.
What do you mean by Schema?
The Schema is the structure of Database System.
What is Database Model?
The database model is a conceptual model to represent the flow of data processing and manipulation techniques.It displays the Blueprint of a database.
What is ER-Model?
The entity-relationship model (or ER model) is a graphical representation of Database Model. ER model uses different types of graphical shapes to represent the different types of the element of database systems.
What is Metadata?
Metadata is the information about other data stored.
What is data dictionary?
The data dictionary is the collection of Metadata. All the metadata are stored in data dictionary.
What is tuple?
A tuple is a row or a record in a table.
What is the unique key?
The unique key is a column of a table that is used to identify a column. It defines a column uniquely.No two rows can have the same unique key. It is used as a constraint to make records unique.
What is a foreign key?
A foreign key is a unique key of a table can is used as a reference in another table. A column in a table can be used to identify records in another table, then It will be a foreign key.
What is a composite key?
A composite key is a combination of keys that functions like a unique key. When two or more columns are required to Identify a record uniquely, then It will be called as a Composite key.
What is Index?
The index is a key that is used to search records in the database. An index makes searching and parsing of data easy. It can be used for sorting or grouping purpose in queries. It improves the runtime of queries.
What is the procedure?
We can say a procedure is a function defined in PL/SQL. It is the collection of multiple Structured Query Language. We cam implement modules in SQL using procedures.
What is a transaction?
A transaction is an independent thread in execution. It can be described on the basis of ACID properties.
Explain ACID properties?
ACID properties are associated with a database transaction. ACID stands for Atomicity, Consistency, Isolation, and Durability. A transaction must maintain these states during its execution.
What is aggregation?
Aggregating the values of many rows to produce an efficient result is known as aggregation in Database System. There are many functions to complete these tasks as SUM, COUNT, AVG etc.
What is normalization?
Normalization is a technique to process over a grouped records organized in tuples.
What are the database languages?
Database systems provide some standard communication that can be used to operate the systems. We can read, update, alter and store data in tables using these languages. For example, SQL is a database Language.
What is DDL – the Data Definition Language?
The database language for creating the structure is known as DDL or Data Definition Language. CREATE, ALTER, and DROP is the DDL parts.
What is DML – the data Manipulation Language?
DML is a tool to read and amend the data stored in the database. SELECT, INSERT, UPDATE are the part of DML.