, Index Performance
, Positive Numbers
, Employee Manager
, Merge Stock Index
, Post Comment
, Row Appender
, Cheapest Product
, Function Wrapper
, Movies Live
, Hide Button
, Truthy Expressions
, Array Search
, ATM Locations
, Department Report
, Delete Orders
, Product Rating
, Restaurant Menu
, Student Activities
, Table of Names
, Word Count
, Log Parser
, Date Transform
, Youngest Child
, SMS Messages
, Scale Font Size
, New Folder
, Log Patch
, Loading Bar
, Bank Branches
, Hospital Patients
, Menu Items
, Ban Users
An array is a container of a fixed number of objects of a similar type. It is a fundamental component of most programming languages.
Closures are an important concept in any programming language in which functions are first-class citizens.
SQL is the dominant technology for accessing application data. It is increasingly becoming a performance bottleneck when it comes to scalability. Given its dominance, SQL is a crucial skill for all engineers.
An aggregate function is typically used in database queries to group together multiple rows to form a single value of meaningful data. A good programmer should be skilled at using data aggregation functions when interacting with databases.
Subqueries are commonly used in database interactions, making it important for a programmer to be skilled at writing them.
The proper implementation and use of indexes are important for improving the performance of database queries.
Conditional statements are a feature of most programming and query languages. They allow the programmer to control what computations are carried out based on a Boolean condition.
Arithmetic is a fundamental branch of mathematics. An understanding of arithmetic concepts, and their application, is important for every candidate.
A programmer should use a language as a tool, always taking advantage of language-specific data types and built-in functions.
Even though most database insert queries are simple, a good programmer should know how to handle more complicated situations like batch inserts.
A normalized database is normally made up of multiple tables. Joins are, therefore, required to query across multiple tables.
In mathematics, a union typically involves testing if an element exists in two or more sets. This definition also applies as an operator and function in various programming languages. As one of the most common collection operations, alongside intersection, it's an important topic for any candidate to understand.
The string data structure is used to represent text. It is one of the most commonly used data structures. Therefore, every programmer should be skilled at string manipulation.
Dynamically accessing and updating user interface elements is an important part of most modern web applications.
Event-based design patterns are very common in modern applications, especially in the development of user interfaces.
Iteration is the act of repeating a process, or cycling through a collection. Iteration is one of the fundamental flow control tools available to developers.
Every programmer should be familiar with data-searching methods, as they are very common in data-analysis processes.
Exceptions exist in most modern programming languages, making it important for a programmer to understand them and know how to handle them.
A good programmer should be familiar with when to use recursive functions, since they can provide elegant solutions for complex problems.
Constraints are used to define rules and relationships. They are applied to a dataset. A constraint may take many forms, such as x ≤ 5 in a programming language and a NOT NULL constraint in a SQL table definition.
A database schema defines how data is stored in a database. An SQL database uses a schema to define tables consisting of rows and columns that use fixed data types to store data. Formalizing how data is stored is the first step towards building an application or service.
Everyone makes mistakes. A good programmer should be able to find and fix a bug in their or someone else's code.
The delete statement is used to delete records in a table and is one of the four basic CRUD functions (create, read, update, and delete) required for working with any persistent storage.
Familiarity with data serialization to and from formats such as XML and JSON is important as it is commonly used for interprocess communication
Every programmer should be familiar with data-sorting methods, as sorting is very common in data-analysis processes.
The UPDATE statement is used to modify the existing records in a table and is one of the most used operations for working with the database.
A database view is a result set that is defined by a stored query, the results of which can can also be queried. As a fundamental and widely used database construct, it's useful for candidates to understand how and when they should be used.
Styling user interfaces according to the specification is a daily routine for a front-end developer.
A class is one of the most widely used and primary structures used in object-oriented programming. As such it's important for any developer to have a working knowledge of how to use it.
Monkey Patching is a method of either adding new or overriding existing functionality without the creation of a new type. As such it's an important tool for developers to be familiar with.
HTML5 is now supported in all modern browsers, making it important for front-end developers to know how to use its features.
The performance of an application or system is important. The responsiveness and scalability of an application are all related to how performant an application is. Each algorithm and query can have a large positive or negative effect on the whole system.