Q181. How to select FirstName from Customers?
To retrieve only the `FirstName` column from the `Customers` table, use the standard `SELECT` projection statement: ```sql SELECT FirstName FROM Customers; ``` ### Perfor...
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Q182. What is the difference between a GET request and POST request?
The GET request is used to retrieve data from a web server, while a POST request is used to submit data to a web server. GET requests are less secure and have limit on th...
Q183. What is a unary function?
A unary function (also known as a **monadic** function) is a function that **accepts exactly one argument**. The term "unary" simply refers to the function's arity—the nu...
Q184. What is "key" prop and what is the benefit of using it in arrays of elements?
A `key` is a special attribute you **should** include when mapping over arrays to render data. _Key_ prop helps React identify which items have changed, are added, or are...
Q185. How do you create a hyperlink in HTML?
Hyperlinks are created using the anchor element (**``**) paired with the essential **`href`** (Hypertext Reference) attribute: ```html Explore Technical Interview Categor...
Q186. What is the difference between interfaces and type aliases in TypeScript? When would you use one over the other?
Interfaces in TypeScript define how an object should look or what a class should implement. They can be extended or implemented by other interfaces and classes. Type alia...
Q187. What is Virtual DOM?
The _Virtual DOM_ (VDOM) is a lightweight, in-memory representation of _Real DOM_ used by libraries like React to optimize UI rendering. The representation of a UI is kep...
Q188. Which statement returns only different values?
`SELECT DISTINCT`. It operates on the *entire selected row*. ```sql -- Returns unique city-state combinations SELECT DISTINCT city, state FROM addresses; ```
Q189. What is the purpose of the alt attribute in HTML?
The alt attribute is used to provide a text description of an image for users who are unable in to see the image, such as those who use screen readers.
Q190. What is a pure function?
A **pure function** is a function whose output depends only on its input arguments and produces no side effects. This means that given the same inputs, a pure function wi...