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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

10 Blockchain Smart Contract Interview Questions

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Here are the  top ten interview questions  on Blockchain smart contracts. Here you will know about smart-contract, what language and IDE you need to develop. Useful for interviews as well. 1. What is a Smart Contract? A  smart contract  is an executable code on the blockchain intended to digitally facilitate, verify, validate, and enforce the rules and regulations of an application. Smart contracts allow the performance of credible transactions without third parties . These transactions are trackable and irreversible. 2. Where the smart Contract code resides? The smart contract is deployed in a sandbox environment and identified by a 160-bit account address like any other participants on the blockchain network. It executes on the virtual machine (VM) on the blockchain node and is identified by an account number. 3. Smart Contract is it API? Yes, it is like a class. It has methods. These are useful to process transactions in the Blockchain framework. 4. What are the six functions of Sm

Hyperledger Fabric: 20 Real Interview Questions

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Hyperledger is one of the top-listed blockchains. This architecture follows R3 Corda specifications. Sharing the interview questions with you that I have prepared for my interview. Though Ethereum leads in real-time applications. The latest Hyperledger version is now ready for production applications. It has now become stable for production applications. The Hyperledger is now backed by IBM. But, it is still an open source. These interview questions help you to read quickly. The below set of interview questions helps you like a tutorial on Hyperledger fabric. Hyperledger Fabric Interview Questions 1). What are Nodes? In Hyperledger the communication entities are called Nodes. 2). What are the three different types of Nodes? - Client Node - Peer Node - Order Node The Client node initiates transactions. The peer node commits the transaction. The order node guarantees delivery. 3). What is Channel? A channel in Hyperledger is the subnet of the main blockchain. You can ha

Blockchain Technology: 11 Exclusive Benefits

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Here are the benefits of blockchain technology. Less maintenance and its distributable nature made the blockchain technology hot in the market.     The applications that used blockchain technology Viz: Banks, Share markets, Government Bodies, and Big Corporations.  What is Blockchain Blockchain stores each transaction in Blocks. No one can tamper or change the details. The people who are making a transaction in the Blockchain world both have the same copies. he parties involved cannot changes these records. So it is robust. Advantages of distributed ledger technology (Blockchain) The distributed nature of ledger details. Distributed data available to all parties, and cannot tamper the data. Every transaction is Public. That means only people who have access can see the information. It stores all records permanently. One cannot edit or manipulate the data. Data-hacking is not possible since it is distributed. Unlike centralized processing, the Blockchain is much faster. And verification

What is Block-linking in Blockchain - Quick Tutorial

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Satoshi Nakamoto created the first Blockchain project wished Bitcoin to be secure, anonymous and could work with no centralized intermediary. To achieve that, Nakamoto combined public-key cryptography, a distributed ledger, and a consensus algorithm. History of Blockchain  Nakamoto combined public-key cryptography, a distributed ledger, and a consensus algorithm. The groundwork for each component was painfully laid by people before him, such as Wei Dai, Nick Szabo, Hal Finney, and Adam Back. The Blockchain can sometimes refer to the combination of all three components or just the distributed ledger. Blockchain ideas As the name aptly describes, at the heart of the Blockchain there is a chain of blocks, each block containing read-only data that represents monetary transactions. Every time a new block is written, you need to reference the block that immediately precedes it – so, at any given point, you can track down the chain up to the very first block created. How blockchain des

Here is an Audio Post Explained About Blockchain

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According to Investopedia - Originally developed as the accounting method for the virtual currency Bitcoin , blockchains – which use what's known as distributed ledger technology (DLT) – are appearing in a variety of commercial applications today. Distributed Ledger 1 - What is the Current Trend All the transactions currently can be edited by the server owners. They have full control to change the transaction details. The current trend is either centralized or decentralized. 2- Distributed Trend No one can edit the transaction details. It is transparent to all stakeholders. Video on Distributed Systems References What is Centralized Server Processing Role of Distributed Server Processing

How to Use Blockchain in Internet of Things and Real Applications

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You do not need a central authority in the blockchain. The distributed nature of records makes the records visible to all the parties. Encrypted blocks link to each other. You cannot manipulate the stored records in the blockchain.   Why the peer-to-peer network and the absence of a central authority Peer to peer network makes secure and transparent transactions. The data in the blocks are encrypted. The distributed nature is the main reason for not having central authority in the blockchain. Blockchain in IoT There are already blockchain applications in the context of the Internet of Things and some vendors have specific solutions to enable the use of blockchain for IoT too, among others increase trust, save costs and speed up transactions.  IBM is a frontrunner , although several vendors and industry initiatives have been launched with new solutions and actual deployments. References Top Blog on Blockchain Technology Trends

The Essential Guide to Blockchain Terminology

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Bitcoin was the first project developed by using blockchain. My post is to share Blockchain keywords by using an example of Bitcoin. Let us ready... Blockchain is new technology. Understanding its principles makes you helpful to apply in your projects.  Initially, the purpose of  Blockchain development was to carry mining. In general, mining means search and find value. Usually, mining processes are two types. Those are data mining and bitcoin mining . Blockchain Glossary Blockchain - only blocks involved. The data which was finalized stored in blocks. Bitcoin Ledger - It is a public ledger Ledger or Blockchain - The chain of blocks Functions of Blockchain - It validates each transaction, Keeps track, and verifies ownership Double Spending- It prevents duplicating the Cryptocurrency for using next time. Consensus mechanism - It is also called PoW (proof of work). This mechanism avoids double-spending Group of Transactions - When a new group of transactions created, t

4 Must read Blockchain Disadvantages for Consumers

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Here are the disadvantages of Blockchain. Below, you will find the list of these. Blockchain Disadvantages Lack of privacy Loss of personal responsibility Loss of jobs Reintermediation 1. Lack of Privacy Public blockchains do not hide any of their data. Instead, everyone can read the complete history of transactions. This level of transparency is frightening for those who want to protect their privacy. These concerns are understandable when considering the level at which personal data are already collected and utilized by large corporations or intelligence agencies. 2. Loss of Responsibility Loss of personal responsibility is often considered a consequence of disintermediation. Intermediaries not only bring different parties of a contract together but may also provide guarantees. They offer reconciliation in cases when transactions do not work out as intended, and they are also obliged to take responsibility for their actions. The shift from trust in people and human organizations to

KYC: Top BlockChain Application Read Today

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SBI is now pressing ahead with its first implementation of the decentralized technology by using an enterprise blockchain solution for managing its Know Your Customer (KYC) system, via a new partnership with Intel that sees the technology giant become the consortium’s official technology advisor. What is KYC Know your customer means all banks update information about their customers. Customer details are Phone number, Aadhar Card, PAN, Home Address, etc. These details are mandatory to update once in six months. Blockchain Platform to Use in KYC is Hyperledger Sawtooth The enterprise blockchain will run on Hyperledger Sawtooth, a modular platform for developing and deploying blockchains, developed by Intel – a member of the open-source Linux Foundation-led Hyperledger project. The blockchain will also be supplemented by Intel Software Guard Extensions (SGX) to boost the blockchain’s privacy, security, and scalability. The blockchain solution will be delivered by Primechain, an Indian bl

The In-and-Out of Nodes in Blockchain

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Blockchain is a decentralized technology or distributed ledger on which transactions are anonymously recorded. Which means the transaction ledger is maintained simultaneously across a network of unrelated computers or servers called “nodes”, like a spreadsheet that is duplicated thousands of times across a network of computers. The ledger contains a continuous and complete record (the “chain”) of all transactions performed which are grouped into blocks A block is only added to the chain if the nodes, which are members in the blockchain network with high levels of computing power, reach consensus on the next ‘valid’ block to be added to the chain. A transaction can only be verified and form part of a candidate block if all the nodes on the network confirm that the transaction is valid. Related 11 Useful Blockchain Advantages to Read now Blockchain Smart Contract The Perfect Example