Frequently asked DBMS and SQL Interview Questions and answers for Freshers, Experienced developers & testers covering topics such as Record, Table, Transactions, Locks, Normalization, Foreign Key, Primary Key, Constraints, SQL Commands, Pattern Matching, SQL Joins, Views, Stored procedure, Trigger, Cluster & Non cluster Index. These questions cover basic and advanced topics on Oracle, MS SQL Server and MySQL Database.
Interview Questions and answers on Database Basics1. What is DBMS ?
Relational Database Management system (RDBMS) is a database management system (DBMS) that is based on the relational model. Data from relational database can be accessed or reassembled in many different ways without having to reorganize the database tables. Data from relational database can be accessed using an API , Structured Query Language (SQL).
Structured Query Language(SQL) is a language designed specifically for communicating with databases. SQL is an ANSI (American National Standards Institute) standard.
1. DDL – Data Definition Language DDL is used to define the structure that holds the data. For example, Create, Alter, Drop and Truncate table.
2. DML – Data Manipulation Language DML is used for manipulation of the data itself. Typical operations are Insert, Delete, Update and retrieving the data from the table. The Select statement is considered as a limited version of the DML, since it can't change the data in the database. But it can perform operations on data retrieved from the DBMS, before the results are returned to the calling function.
3. DCL – Data Control Language
DCL is used to control the visibility of data like granting database access and set privileges to create tables, etc. Example - Grant, Revoke access permission to the user to access data in the database.
5. What are the Advantages of SQL ?
1. SQL is not a proprietary language used by specific database vendors. Almost every major DBMS supports SQL, so learning this one language will enable programmers to interact with any database like ORACLE, SQL ,MYSQL etc.
2. SQL is easy to learn. The statements are all made up of descriptive English words, and there aren't that many of them.
3. SQL is actually a very powerful language and by using its language elements you can perform very complex and sophisticated database operations.
6. what is a field in a database ?
A field is an area within a record reserved for a specific piece of data.
Examples: Employee Name, Employee ID, etc.
7. What is a Record in a database ?
A record is the collection of values / fields of a specific entity: i.e. an Employee, Salary etc.
8. What is a Table in a database ?
A table is a collection of records of a specific type. For example, employee table, salary table etc.