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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

All About Init and Delete Constructors Python

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Python class has two constructors. One is the init, and the other one is del. Why do you need these two and their real purpose explained? The initialization method is called __init__ while the finalization or destructor method is called __del__. Python methods with a double underscore character are for internal (not intended for direct access by the outside world) use. There are no true private methods in Python classes, but convention says that a method that begins with a single underscore is considered private, and a double underscore indicates it is internal (only to be used by the system.) Python Constructors  Init Constructor object.__init__(self[, ...]) Called after the instance has been created (by  __new__() ), but before it is returned to the caller. The arguments are those passed to the class constructor expression.  If a base class has an  __init__()  method, the derived class’s  __init__()  method, if any, must explicitly call it to ensure proper initialization of the base