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SQL Interview Success: Unlocking the Top 5 Frequently Asked Queries

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 Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. Top SQL Queries for Interviews 01. Joins The commonly asked question pertains to providing two tables, determining the number of rows that will return on various join types, and the resultant. Table1 -------- id ---- 1 1 2 3 Table2 -------- id ---- 1 3 1 NULL Output ------- Inner join --------------- 5 rows will return The result will be: =============== 1  1 1   1 1   1 1    1 3    3 02. Substring and Concat Here, we need to write an SQL query to make the upper case of the first letter and the small case of the remaining letter. Table1 ------ ename ===== raJu venKat kRIshna Solution: ========== SELECT CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS capitalized_name FROM Table1; 03. Case statement SQL Query ========= SELECT Code1, Code2,      CASE         WHEN Code1 = 'A' AND Code2 = 'AA' THEN "A" | "A
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AWS Cloud Computing Tutorial for Beginners

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Complete tutorial for beginners on AWS. Also explained AWS security features.


1. What you can do with AWS

  • Store public or private data.
  • Host a static website. These websites use client-side technologies (such as HTML, CSS, and JavaScript) to display content that doesn't change frequently. A static website doesn't require server-side technologies (such as PHP and ASP.NET).
  • Host a dynamic website, or web app. These websites include classic three-tier applications, with web, application, and database tiers.
  • Support students or online training programs.
  • Process business and scientific data.
  • Handle peak loads.

2. AWS (Amazon Web services different features)


  • AWS Management Console A web interface. To get started, see the Getting Started with the AWS Management Console.
  • AWS Command Line Interface (AWS CLI) Commands for a broad set of AWS products.To get started, see AWS Command Line Interface User Guide. Command Line Tools Commands for individual AWS products.
  • For more information, see Command Line Tools. AWS Software Development Kits (SDK) APIs that are specific to your programming language or platform. For more information, see SDKs.

Basics of AWS and its features explained for beginner cloud computing engineers.


Query APIs Low-level APIs that you access using HTTP requests. For more information, see the API documentation for each service. 


3. Global Security Features in AWS

  1. Physical access to AWS data centers is strictly controlled, monitored, and audited.
  2. Access to the AWS network is strictly controlled, monitored, and audited.
  3. You can manage the security credentials that enable users to access your AWS account using AWS Identity and Access Management (IAM).You can create fine-grained permissions to AWS resources and apply them to users or groups of users.
  4. You can apply ACL-type permissions on your data and can also use encryption of data at rest.
  5. You can set up a virtual private cloud (VPC), which is a virtual network that is logically isolated from other virtual networks in the AWS cloud.You can control whether the network is directly routable to the Internet.
  6. You control and configure the operating system on your virtual server.
  7. You can set up a security group, which acts as a virtual firewall to control the inbound and outbound traffic for your virtual servers.
  8. You can specify a key pair when you launch your virtual server, which is used to encrypt your login information. When you log in to your virtual server, you must present the private key of the key pair to decrypt the login information.

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