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SQL Query: 3 Methods for Calculating Cumulative SUM

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SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT t1.id, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON t1.id >= t2.id GROUP BY t1.id, t1.value ORDER BY t1.id; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or

5 AWS Tricky Interview Questions

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Below are the top tricky questions asked in AWS interviews 1) How do you store objects in Reduced Redundancy Storage in S3? Specify REDUCED_REDUNDANCY tags in the HTML code. Specify REDUCED_MIRRORING on a PUT request using an optional header. Specify LOW_REPLICATION on a PUT request using an optional header. Specify LOW_REPLICATION on a GET request for objects. Specify REDUCED_REDUNDANCY on a PUT request using an optional header. 2) Which is required to log on to the AWS management console on a mobile device? SSO alias SiteMinder Gateway address IAM token AWS account 3) How do you receive notifications based on the value of a metric being above or below a stated threshold in Amazon CloudWatch? Set Amazon SmartAlert. Log on through the Amazon console. Create an Amazon CloudWatch threshold dashboard. Create an Amazon CloudWatch alarm. Create a DescribeAlarmHistory API. 4) Scenario-You are testing Oracle, SQL Server, and Mongo DB databases in your AWS account to determine which database t

12 Top Hadoop Security Interview Questions

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Here are the interview questions on Hadoop security. Useful to learn for your data science project and for interviews.  12  Hadoop Security Interview Questions How does Hadoop security work? How do you enforce access control to your data? How can you control who is authorized to access, modify, and stop Hadoop MapReduce jobs? How do you get your (insert application here) to integrate with Hadoop security controls? How do you enforce authentication for users on all types of Hadoop clients (for example, web consoles and processes)? How can you ensure that rogue services don't impersonate real services (for example, rogue Task Trackers and tasks, unauthorized processes presenting block IDs to Data Nodes to get access to data blocks, and so on)? Can you tie in your organization's Lightweight Directory Access Protocol (LDAP) directory and user groups to Hadoop's permissions structure? Can you encrypt data in transit in Hadoop? Can your data be encrypted at rest on HDFS? How can

5 top data warehousing questions to read before interview

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Hey, welcome to data analytics. Here I have given a few questions and answers. The below five questions helps you to understand very basics on data analytics. These are very basic questions. But, for laymen, they can understand easily and also good for interviews. Stocksnap.io Questions on Business Intelligence What is Business Intelligence?  It is a well-established process in the business world whereby decision makers integrate strategic thinking with IT  What is Web Analytics?  It is the collection, analysis, and reporting of Web site usage by visitors and customers of a website in order to better understand the effectiveness of online initiatives and other changes to the website in an objective, the scientific way through experimentation, testing, and measurement.  What is academic analytics?  This is the area analytics applied in academia  What is action analytics?  This is the area of analytics to produce actionable intelligence  What is the process of