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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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How to Call SQL Query from Python

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Python's top supported database is MySQL. You can run SQL queries from Python. Here're best examples of how to connect to MYSQL and access MYSQL tables from Python.


Read: How to Print String in Next Line Easily


Here are Steps

  1. Import MySQL connecter
  2. Give user id, password details
  3. Issue SQL query


Python Logic to import MySQL connector


import mysql.connector


Note: If the MySQL connecter not installed in python, you need to install it using the below command.


pip3 install mysql-connector-python --allow-external mysql-connector-python


How to Call SQL Query from Python



Supply user id and Password


conn=mysql.connector.connect(user='root', password='password', host='localhost', database='sakila')



mycursor=conn.cursor()


Issue SQL Query



mycursor.execute("show tables") # you won't see any result. You need to give print.


print(mycursor.fetchall())


mycursor.execute("select * from customer") # you won't see any result. You need to give print.


print(mycursor.fetchall())


This way you can issue SQL queries in Python.


Read: Top 100 Hadoop Interview Questions 1 of 4

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