Mefron Interview Questions and Answers

Nested classes in Java have a hierarchical structure with the outer class containing the inner class, which can further contain more inner classes.

• Nested classes are defined within another class, known as the outer class.

• Inner classes have access to the members of the outer class.

• Nested classes can be static or non-static.

• The calling sequence for nested classes is OuterClass.InnerClass.method();

• Example: OuterClass outer = new OuterClass(); OuterClass.InnerClass inner = outer....read more

Oops concepts refer to Object-Oriented Programming principles like Inheritance, Polymorphism, Encapsulation, and Abstraction.

• Inheritance: Allows a class to inherit properties and behavior from another class.

• Polymorphism: Ability of objects to take on multiple forms.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Abstraction: Hiding the complex implementation details and showing only the necessary features.

Dotnet is a software framework developed by Microsoft for building and running applications on Windows.

• Dotnet is a platform that provides tools and libraries for developing various types of applications.

• It supports multiple programming languages such as C#, VB.NET, and F#.

• Dotnet includes a runtime environment called Common Language Runtime (CLR) which manages the execution of code.

• It also includes a class library called Framework Class Library (FCL) which provides reusable co...read more

To delete duplicate rows, we can use the DISTINCT keyword or GROUP BY clause in SQL.

• Use the DISTINCT keyword to select unique rows from a table.

• Use the GROUP BY clause to group rows with the same values and select only one row from each group.

• Use the HAVING clause with GROUP BY to filter out groups with more than one row.

• In Informatica, use the Sorter transformation to sort the data and then use the Aggregator transformation with the Group By option to remove duplicates.

Truncate removes all data from a table while delete removes specific rows.

• Truncate is faster than delete as it doesn't log individual row deletions

• Truncate cannot be rolled back while delete can be

• Truncate resets the identity of the table while delete doesn't

• Truncate doesn't fire triggers while delete does

Star and snowflake are two types of database schema used in data warehousing.

• Star schema is simpler and easier to understand.

• Snowflake schema is more normalized and reduces data redundancy.

• Star schema is better for simple queries and reporting.

• Snowflake schema is better for complex queries and analysis.

• Star schema has fewer tables and is faster for querying.

• Snowflake schema has more tables and is slower for querying.

• Star schema is denormalized while snowflake schema is normal...read more