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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
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Vi Editor to Quit use Esc and Colon

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Here are vi editor commands you can use to quit from Vi editor with or without saving your work. These are useful to use in day-to-day work.

w => To Save Your Work
q => To Quit
wq => To Save and Quit
q! => To quit without saving


vi editor also called Visual editor in terms of Unix or Linux or Ubuntu Operating systems. Since all are the same UNIX flavor, and UNIX is the mother of all these operating systems.


Recently many of my friends asked to share some daily use vi editor commands. I am sharing those for your quick reference.

6 Top vi Editor Commands


1. How to Edit a file?

vi filename

This is the first command to use for editing a file.


2. A command to Repeat Previous Command?

Use the UP arrow to repeat the previous command.


3. How to Insert data?

Use insert command to over-type data.


4. How to Save File?

Press Esc
then
:w

5. How to Save and Quit (Exit)?

Press Esc
then
:wq

6 How to quit without Save?

Press Esc
then
:q!

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