News
IBM to offer mobile security as a service IBM will start delivering mobile security-as-a-service (MaaS) through its own cloud infrastructure in India, a move that is expected to better address in-country data requirements... IBM Spectrum Computing: IBM has enlarged its portfolio of software-defined infrastructure solutions with cognitive features for workload management.  * LiFi internet technology has been introduced, the new type of wireless internet connection that gives 100 times faster than traditional WiFi -- Invented by Professor Harald Haas from the University of Edinburgh. * Sci. Rachid Yazami has developed a smart chip that charges smartphones in less than 10 minutes. BenQ has launched BlueCore projector - Consumer electronics major BenQ has launched its first BlueCore laser light source projector. For those unaware, devices with BlueCore laser technology have a high contrast output of 80000:1 with an extended lamp life and efficiency. ***
Category - SQL Interview Questions
 
1. What is RDBMS?
Ans:
  • DBMS is a layer of abstraction between application and database.
  • Application interact with the Database via DBMS using Structure Query Language(SQL).
  • If the database is logically in the form of tables i.e., relation then we call this DBMS as RDBMS.

2. What is Relation in RDBMS?
Ans:
A table in a database is called as relation.

3. What is Tuple?
Ans:
A Row of a table in database is called as tuple.

4. What is Primary Key?
Ans:
  • Primary Key is a column of a table which is used to identity a row uniquely.
  • Primary Key cannot have NULL values.
  • Primary Key cannot have duplicate values.

5. What is Unique Key?
Ans:
  • Unique Key is a column in a table which does not allow duplicate values like primary key.
  • It allows one and only one NULL values.
  • A table can have one and only one primary key.
  • A table can have one or more unique keys.

6. What is Foreign key?
Ans:
  • Foreign key is a column of one table which refers to the Primary Key column of another table.
  • It allows NULL values.
  • It allows Duplicate values.

7. What is use of Group by clause?
Ans:
  • Group by clause is used to display data by combining or grouping one or more columns.
  • Group by clause is always is used in combination with Aggregate Functions.
  • Basically Group By clause comes after Where Clause and before Having Clause.
  • The typical order of clauses in a query is WGHO (W-Where, G-Group By, HHaving, O-Order By) in most of the queries

8. What is Having Clause?
Ans:
  • Having clause is similar to where clause.
  • Having clause is used to filter the column generated by aggregate functions.
  • As where clause cannot be used with aggregate functions.

9. What is SQL ?
Ans:
Structured Query Language(SQL) is a language designed specifically for communicating with databases. SQL is an ANSI (American National Standards Institute) standard.

10. What are the different type of SQL's statements ?
Ans:
This is one of the frequently asked SQL Interview Questions to freshers. SQL statements are broadly classified into three. They are
  • DDL – Data Definition Language
DDL is used to define the structure that holds the data. For example, Create, Alter, Drop and Truncate table.

  • 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. Select statement is considered as a limited version of DML, since it can't change data in the database. But it can perform operations on data retrieved from DBMS, before the results are returned to the calling function.

  • 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 database.

123
Search
Recent Posts
Bind Gridview from CSV file in Asp.Net C#
Jun 18 2017 11:38PM Posted By Michael
Call WebService method from jQuery in every 1 minute
Feb 27 2017 11:51AM Posted By John
Gridview custom CSS in ASP.Net
Feb 25 2017 10:59AM Posted By Micheal Ryan
Read excel file and bind to Gridview in C#
Feb 25 2017 10:20AM Posted By Micheal
Read excel file and convert to List in C#
Feb 25 2017 6:26AM Posted By Michael
Encryption and Decryption for Password in C#
Feb 17 2017 3:52AM Posted By Michael
How to create Chart in ASP.Net C#
Feb 16 2016 8:03AM Posted By Michael Ryan
Tags
Follow us on Facebook
Follow us on Google +
Recent post in your Email inbox.
Enter your email address: