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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 Abstract Classes to Learn Quickly

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Here's the best example of how to understand the abstract classes of python quickly. An abstract class means it is a skeleton. You cannot instantiate abstract classes. For Example: The abstract class name is 'dog' o = dog() It gives an error. Since the ' dog' is an abstract class. I am sharing with you a clear understanding of abstract class. So that you can tell confidently about these classes. The syntax for Abstract Class from abc , import ABC , abstractmethod  class <class name>(ABC): @abstractmethod  def <method name>():  #abstract class definition Python Abstract Class Explanation from abc import ABC, abstractmethod class AbsBaseClass(ABC): def __init__(self): print("Abstract class") @abstractmethod def abMeth(self): pass def conMeth(self): print("I'm a concrete method") class Derived(AbsBaseClass): def abMeth(self): print("I'm redefined") o=Derived() o.abMeth() o.conMeth() References Star Python Certification