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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