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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

Python: Here are 3 Brilliant Methods to Execute

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You can run python commands in three methods. Those are at CLI, Python interface, and as a Script. How to Run Script at CLI? The script extension should be .py. Here is an example xyz.py. When the script is ready, the next step is to run it. How to run it from CLI?  Here is a command to run at CLI. Suppose you have installed Python in Linux OS. Then you need to give: $ python -m xyz.py Here, m means module. That means you are running a script with Python code. How to Run Commands at Script? The Other way, you can execute Python statements directly at CLI. Here's a command for your quick reference. $ python -c "print('Hello world')" Here, the print statement displays " Hello World " on the screen. How to Run commands at Python Interface? You know that the Python interface needs an operating system - Windows or Linux.  $ Python3 >>> 10 + 20 30 References Python Programming: Using Problem Solving Approach

Hadoop fs (File System) Commands List

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Hadoop HDSF File system commands given in this post. These are useful for your projects and interviews. HDFS commands HDFS File System Commands. Hadoop fs -cmd <args> cmd is a specific command and arg is the variable name.  The List of Commands cat  Hadoop fs –cat FILE [FILE …]  Displays the files' content. For reading compressed files.  chgrp  Hadoop fs –chgrp [-R] GROUP PATH [PATH …]  Changes the group association for files and directories. The – R option applies the change recursively.  The user must be the files' owner or a superuser.  chmod  Hadoop fs –chmod [-R] MODE[,MODE …] PATH [PATH …]  Changes the permissions of files and directories. Like, its Unix equivalent, MODE can be a 3-digit octal mode, or {augo}+/-{rwxX}. The -R option applies the change recursively. The user must be the files' owner or a superuser.  chown  Hadoop fs –chown [-R] [OWNER][:[GROUP]] PATH [PATH…]  Changes the ownership of files and directories. The –R option applies the change recursiv

vi Editor Top Commands for Ubuntu OS

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I have given VI editor commands to use in Ubuntu operating system. You can practice using them for your benefit and you can complete your work quickly. To begin changing or adding to text with vi, you can enter Insert or Replace modes, as shown in the following list. When you enter Insert or Replace mode, the characters you type will appear in the text document (as opposed to being interpreted as commands).  vi filename This is the first command to enter into editor mode. Once you enter into editor mode, you need to enter other commands to complete your editing work. Press the Esc key t o exit to Normal mode after you are done inserting or replacing text. List of VI Editor Commands.. i—Typed text appears before current character. a—Typed text appears after current character. o—Open a new line below current line to begin typing. s—Erase current character and replace with new text. c?—Replace ? with l, w, $, or c to change the current letter, word, end of line, or line. r—Repla