Difference Between Primary, Foreign and Unique Keys

In SQL, keys are used to identify records present in a database. The keys used in SQL may look identical but their behaviour is entirely different. The difference between primary, unique and foreign keys is one of the most important concepts in relational database management. The difference between keys is also a common SQL interview […]

Difference Between HAVING Clause and GROUP BY Statements

The difference between the HAVING Clause and GROUP BY statement is common question asked in the database interviews. Both HAVING and GROUP BY are used as an extension of SQL queries. These extended SQL queries are used to filter the rows and return a particular value. HAVING clause and GROUP BY statements play an important […]

SQL: Inner vs Outer join

To comprehend the difference between the two types of joins i.e. inner join and Outer join in SQL, let’s first revise the basic knowledge about the join in SQL, the inner join and the outer join. What is a join in SQL? A join in SQL may be defined as a way which is used […]

SQL: Clustered vs non clustered Index

An index in SQL may be defined as a structure linked with a particular table and is stored on the disk, mainly created to enhance the speed of the retrieval of data. The key for an index in SQL is created from one or more than one column present in a particular table or even […]

SQL questions: What is an index?

An Index in SQL may be defined as the secondary database object which is connected to a specific table to enhance the process of retrieval of the associated rows from that particular table. It can be defined for a specific single column or for multiple columns. We can also view an index of SQL as […]

SQL - Difference between Primary and Foreign Key

To understand the difference between PRIMARY KEY and FOREIGN KEY in SQL, you first need to understand the definition of a PRIMARY KEY as well as a FOREIGN KEY. SO, Read: More Interview Questions PRIMARY KEY: It can be defined as a unique column or a group of few columns which are chosen to identify […]

SQL & .NET interview questions and answers

Interview questions and answers of SQL & .NET: Majority of IT company placement interviews are based on .NET programming and SQL databases. In dot NET era, VB.NET and C#.NET are to be used in windows application development meanwhile ASP.NET will be used in online apps development and website designing. At the same time SQL is […]

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