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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

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

Tokenization: Vault based Vs Vault-less

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Tokenization means generating a random number as an alternative for a Credit card (PAN) number. The random number can be Numeric/Non-numeric. It is in such a format that others cannot decode it.    *** The popular tokenization server is the Vault server. It generates a random Token for each transaction customer made at Merchant outlets. You can find how card numbers are masked with junk characters in the pdf provided. Here is the  Visa Security Tokenization Pdf. Two Top Tokenization Servers. Vault based server Vault-less server What is Tokenization? 1. Vault based server It stores a  Card number (PAN) and a Token  in a Table of the Teradata database as Key and value pairs. Due to the growing volume of transactions, the handling of the database became a big challenge for acquirers.  For each transaction, the vault server stores a record. That row contains both the Credit card number and its Token. When you use the same card multiple times, it generates different Tokens.  It is

What You Need to Know About DBA Administrator Responsibilities

Here are helpful DBA interview questions. Read these before your next interview. Your chances to get a job are more. DBA Responsibilities    References DBA role responsibilities e-book  

How to use Blockchain on Cloud

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Blockchain applications are growing in the financial world. Security is the main motto behind blockchain applications. You cannot tamper a record once created. What is a platform   A platform is a place where you can develop applications. Top Blockchain Cloud Platforms The development needs to create a project and deploy it into production. So that the real use can feel by users at their end. Ok... Let us come to three popular cloud platforms that are highly used in Blockchain applications: HyperLedger IBM BlueMix Microsoft Azure #1. HyperLedger The Hyperledger project is led by Executive Director Brian Behlendorf, who has decades of experience dating back to the original Linux Foundation and Apache Foundation, as well as being a CTO of the World Economic Forum. So it's not surprising that Hyperledger has been well received. You can learn hyper Ledger here. Many of the top business and industry leaders have joined the project, including Accenture, Cisco, Fujitsu

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