Chetu Interview Questions, Process, and Tips

An interface is a contract that specifies the methods and properties that a class must implement.

• An interface defines a set of methods and properties that a class must implement

• Interfaces are used to achieve abstraction and polymorphism

• Interfaces can be used to define contracts between different parts of a system

• A class can implement multiple interfaces

• Example: The IDisposable interface in C# is used to ensure that an ...read more

Delete removes specific rows while truncate removes all rows from a table.

• Delete is a DML command while truncate is a DDL command.

• Delete is slower than truncate as it logs each row deletion while truncate only logs the deallocation of data pages.

• Delete can be rolled back while truncate cannot be rolled back.

• Delete can have a WHERE clause to specify which rows to delete while truncate removes all rows.

• Delete does not re...read more

Sealed classes are classes that cannot be inherited and are used to restrict class hierarchy.

• Sealed classes are declared using the 'sealed' keyword.

• They can have abstract members but cannot be instantiated.

• They are useful in creating exhaustive when expressions.

• They restrict the inheritance hierarchy and prevent unintended subclassing.

• Example: sealed class Shape { abstract fun draw() }

Union combines and removes duplicates while Union All combines all rows.

• Union is used to combine the result sets of two or more SELECT statements into a single result set with no duplicates.

• Union All is used to combine the result sets of two or more SELECT statements into a single result set with all rows.

• Union is slower than Union All because it has to remove duplicates.

• Union requires that the number and order of colu...read more

Abstract class is a class that cannot be instantiated and can only be inherited by other classes.

• An abstract class can have abstract and non-abstract methods.

• Abstract methods have no implementation and must be implemented by the child class.

• Non-abstract methods can have implementation and can be inherited by the child class.

• An abstract class can have constructors and variables.

• Example: abstract class Animal { abstract

Primary key uniquely identifies a record while foreign key refers to a primary key in another table.

• Primary key is a column or set of columns that uniquely identifies a record in a table

• Foreign key is a column or set of columns that refers to a primary key in another table

• Primary key cannot have null values while foreign key can have null values

• Primary key is used to enforce data integrity while foreign key is used to