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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 Create an Array and Its Types in Python

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Python supports various array types. Here is a list of arrays and how to create examples for your reference. 

What is an array?


A Python array is a class that mimics the array type of other languages and offers efficiency in storage, exchanging that for flexibility.

How to create an array


Here is the syntax to create an array:

data = array('f', [12.8, 5.4, 8.0, 8.0, 9.21, 3.14])


It creates an array of 6 floating point numbers; the type is indicated by the 'f' as the first parameter to the constructor. This concept is unlike the Python norm of types being dynamic and malleable. An array is an array of one kind of thing, and an array can only hold a restricted set of types.


Array types

Types of arrays

Here is a list of arrays:

'b' A C++ char type
'B' A C++ unsigned char type
'i': A C++ int type
'l': A C++ long type
'f': A C++ float type
'd': A C++ double type

What is an array type?

Arrays are class objects and are provided in the built-in module array, which must be imported:

from array import array

An array is a sequence type and has the basic properties and operations that Python provides for all sequence types. Array elements can be assigned to and can be used in expressions, and arrays can be searched and extended like other sequences.

Tips: I have referred some best books and Udemy course. I am giving here for your ready reference. The best Udemy course is Python Bootcamp and the best Python book is Python pocket primer.
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