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Python Set Operations Explained: From Theory to Real-Time Applications

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A  set  in Python is an unordered collection of unique elements. It is useful when storing distinct values and performing operations like union, intersection, or difference. Real-Time Example: Removing Duplicate Customer Emails in a Marketing Campaign Imagine you are working on an email marketing campaign for your company. You have a list of customer emails, but some are duplicated. Using a set , you can remove duplicates efficiently before sending emails. Code Example: # List of customer emails (some duplicates) customer_emails = [ "alice@example.com" , "bob@example.com" , "charlie@example.com" , "alice@example.com" , "david@example.com" , "bob@example.com" ] # Convert list to a set to remove duplicates unique_emails = set (customer_emails) # Convert back to a list (if needed) unique_email_list = list (unique_emails) # Print the unique emails print ( "Unique customer emails:" , unique_email_list) Ou...
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SQL Tester Ideas DATE, Numeric, CHAR, NULL

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I have shared top SQL Date functions along with Numeric, CHAR and NULL functions.
sql examples on built-in functions


List of Built-in Functions

  1. DATE-TIME functions
  2. Numeric functions
  3. Char functions
  4. Null-related functions

1. DATE/TIME functions

SELECT p_code,
launch_dt,
CURRENT_DATE
FROM product;

CURRENT_DATE returns the CURRENT date.

SELECT p_code,
To_char(launch_dt, 'DD MONTH YYYY') reformatted_dt
FROM product;
TO_CHAR FUNCTION returns date IN char format.

2. Numeric functions

SELECT p_code,
price,
(price - 20),
Abs(price - 20.00)
FROM product;


ABS - FUNCTION returns the absolute value


SELECT p_code,
price,
Round (price, 1)
FROM product;


ROUND FUNCTION - round TO 1 digit.


SELECT p_code,
price,
Sign(price - 15)
FROM product;


SIGN FUNCTION - it returns the sign

SELECT p_code,
price,
Trunc(price, 1)
FROM product;


TRUNC FUNCTION - truncates TO a certain number OF decimal places.


3. CHAR functions

SELECT p_code,
Concat(Concat(p_name, ' -- ') , price)
FROM product;CONCAT FUNCTION - concats two strings.




SELECT p_name,
Lower(p_name),
Upper(p_name)
FROM product;


UPPER FUNCTION : returns upper CASE.
Lower FUNCTION returns lower CASE.




SELECT p_name,
Length(p_name)
FROM product;LENGTH FUNCTION
returns length OF the string.


SELECT Substr(phone, 3)

FROM customer;


SUBSTR FUNCTION : returns a substring FROM the main string.


4. Null related functions

SELECT p_name,
price,
min_price,
COALESCE((price * 0.9), min_price, 5.0) sale_price
FROM product;


COALESCE FUNCTION: returns the first non-NULL value FROM the expression.



Summary
  • Given a list of top built-in functions
  • Example SQL queries on built-in function given for you to read quickly
  • These examples are almost common in any RDBMS

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