TO THE NEW Associate Technical Leader Interview Questions, Process, and Tips for Experienced

first() returns the first element of a sequence, while FirstOrDefault() returns the first element or a default value if the sequence is empty.

• first() throws an exception if the sequence is empty, while FirstOrDefault() returns a default value (e.g. null) in that case.

• Use first() when you expect the sequence to always have at least one element, and FirstOrDefault() when the sequence might be empty.

• Example: var numbers =...read more

Left join includes all records from the left table and matching records from the right table, while right join includes all records from the right table and matching records from the left table.

• Left join: includes all records from the left table and matching records from the right table

• Right join: includes all records from the right table and matching records from the left table

• Example: Left join - SELECT * FROM table1...read more

Optimizing SQL queries involves using indexes, minimizing joins, and avoiding unnecessary columns.

• Use indexes on columns frequently used in WHERE clauses

• Minimize the use of JOIN operations

• Avoid selecting unnecessary columns in the query

• Consider using stored procedures for frequently executed queries

One tool used to check query slowness is SQL Server Profiler.

• SQL Server Profiler can be used to trace and analyze query performance.

• It provides detailed information on query execution, including duration, reads, writes, and more.

• Users can identify slow queries and optimize them for better performance.

• Other tools like Query Store in SQL Server Management Studio can also be used for monitoring query performance.

Repository pattern using EF core for data access layer

• Create an interface for the repository with generic CRUD methods

• Implement the repository interface with EF core for data access

• Use dependency injection to inject the repository into services

• Separate concerns by having repositories handle data access logic