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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

Storage area network: Quick Definition

SANs are primarily used to enhance storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear to the operating system as locally attached devices. A SAN typically has its own network of storage devices that are generally not accessible through the local area network (LAN) by other devices. The cost and complexity of SANs dropped in the early 2000s to levels allowing wider adoption across both enterprise and small to medium-sized business environments.   Best Uses of Storage Area Networks A SAN does not provide file abstraction, only block-level operations. However, file systems built on top of SANs do provide file-level access, and are known as shared-disk file systems. More to read: Best SAN Storage area networks acronyms Top 20 benefits of SAN Storage area networks

8 Useful Books to Change Your Mindset

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I have given eight useful books. These are useful to change your mindset. 1.  10 Percent Entrepreneur Everyone knows that building a startup means hard work and long hours, with payment in stock that may turn out to be worthless. Indeed, that’s part of the glamour. But it also keeps some people with good ideas from getting started. Patrick J. McGinnis, a Wall Street venture capitalist, says don’t worry: You can “live your startup dream without leaving your day job.” Devote 10 percent of your time and capital to pursuing your dream, McGinnis says, and you can keep your job and the security that goes with it. McGinnis, who identifies himself as a 10-percenter, provides a detailed plan to identify a promising first project. He shows how to invest resources in a savvy way, and how to develop something you love doing into a business. Best of all, until you reach your dream of an independent business, McGinnis promises you will perform better at your day job with a step-by-step pl

SAN: Real Architecture Explained

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A SAN is connected behind the servers. SANs provide block-level access to shared data storage. Block level access refers to the specific blocks of data on a storage device as opposed to file level access. One file will contain several blocks. Storage Area Networks (SANs) SANs provide high availability and robust business continuity for critical data environments. SANs are typically switched fabric architectures using Fibre Channel (FC) for connectivity. The term switched fabric refers to each storage unit being connected to each server via multiple SAN switches also called SAN directors which provide redundancy within the paths to the storage units. This provides additional paths for communications and eliminates one central switch as a single point of failure. Ethernet has many advantages similar to Fibre Channel for supporting SANs. Some of these include high speed, support of a switched fabric topology, widespread interoperability, and a large set of management tools. In a st

Storage area network (SAN): Networks Vs Configurations

These are most popular terms used in Storage area networks area. Every developer must know these terms clearly. Highly useful to explain in interviews. Frequently used terminology in SAN given below for your quick reference. 

SAN Vs NAS Benefits, Differences

SANs are particularly helpful in backup and disaster recovery.  Within a SAN, data can be transferred from one storage device to another without interacting with a server. 

19 Top Unix File Scenario Commands

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ETL developers main task is to browse various flat files before they start testing. File browsing in UNIX is tricky. If you know right command to do it you can save a lot of time. These 19 top UNIX files commands useful to use in your project. In UNIX a file normally can have Header, Detail and Trailer. There are scenarios where you need only details without header and Trailer, and need only recent one record, and you need to skip some records from the input files. So for all the File based scenarios, I have given useful UNIX commands.   1). How to print/display the first line of a file?  There are many ways to do this. However the easiest way to display the first line of a file is using the [head] command.  $> head -1 file. Txt If you specify [head -2] then it would print first 2 records of the file.  Another way can be by using [sed] command. [sed] is a very powerful text editor which can be used for various text manipulation purposes like this.  $> sed '2,$ d

4 Top Data Mining Tools

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Many data mining tools present out of those listed here top free tools useful for development. 4 Top Data Mining Tools 1. Rapid Miner (erstwhile YALE) This is very popular since it is a ready-made, open-source, no-coding-required software, which gives advanced analytics.  Written in Java, it incorporates multifaceted data mining functions such as data preprocessing, visualization, predictive analysis, and can be easily integrated with WEKA and R-tool to directly give models from scripts written in the former two. 2. WEKA This is a JAVA based customization tool, which is free to use. It includes visualization and predictive analysis and modeling techniques, clustering, association, regression, and classification. 3. R-Programming Tool This is written in C and FORTRAN and allows the data miners to write scripts just like a programming language/platform. Hence, it is used to make statistical and analytical software for data mining. It supports graphical analysis, both linear and nonlinea