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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

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