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Grouping Data with GROUP BY

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Introduction: What’s the Big Deal About Groups? The GROUP BY Magic Word: How It Works Let’s See It in Action! (Query Examples) Practice Time! (Practice Questions) Solutions to Practice Questions: Stepping Up Your Game: Interview Questions Explain the use of HAVING here.) Grouping Makes Sense! You’ve got a fantastic topic here! By explaining GROUP BY in a way that resonates with a younger audience, you’ll be making a valuable contribution to demystifying databases for everyone. Let me know if you’d like to explore any of these sections in more detail!

Aggregate Functions

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Imagine you’re a detective, and you have a big box of clues (that’s your MySQL database!). Sometimes, you don’t need to look at every single clue in detail. Instead, you want to get a quick summary, like “How many clues do I have in total?” or “What’s the most important clue?”. That’s where aggregate functions come in! They help us summarize information from our database in a snap. Here are the five superstar aggregate functions we’ll learn about today: Let’s say we have a table called candies with information about different candies: candy_name price quantity Chocolate 10 50 Lollipop 5…

Deleting Data

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Hey there, young data explorer! 🚀 Today, we’re going to learn about deleting data from a database using the DELETE statement in MySQL. Imagine your database is like a giant notebook where you write down a list of your favorite games, movies, or snacks. But what if you no longer like one of them? You would erase it, right? That’s exactly what DELETE does in MySQL—it removes unwanted data! Let’s dive in with simple examples, practice questions, and interview questions to master DELETE like a pro. 🔥 1. What is the DELETE Statement? The DELETE statement is used to remove…

Updating Existing Data

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Hey there! 👋 Today, we’re going to talk about updating existing data in MySQL using the UPDATE statement. Imagine you have a notebook 📒 where you wrote down your friend’s phone number, but now they have a new one. Instead of erasing the old number and writing a new one, you just update it. That’s exactly what we do in a database with UPDATE! Let’s dive in! 🚀 📌 What is the UPDATE Statement? The UPDATE statement in MySQL allows you to modify existing records in a table. It helps in changing values without deleting or inserting new rows. 📝…

Inserting Data into Tables

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Imagine you have a big notebook where you write down details about your favorite superheroes. Each page represents a database table, and every row is a new superhero you add to your list. In SQL, we use the INSERT statement when we want to add new information to a table. Let’s explore how we can insert new data into a table using SQL! 🚀 Understanding the INSERT Statement The INSERT statement helps us add new rows to a table. The basic structure of an INSERT statement looks like this: Breaking It Down: Example: Inserting Data into a Table Let’s say…

Persistent Systems’ Sr Python Developer Hiring Challenge (2025)

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Fitness Challenge (100 Marks) Samantha and Jessica are two sisters who are preparing for their annual fitness challenge. They both have been assigned a personal trainer who has given them a workout plan for the next few weeks. The plan includes a set of N exercises, and for each exercise, there is a recommended number of sets and repetitions. Samantha and Jessica have been keeping track of the number of sets and repetitions they have completed for each exercise. At the end of each day, they compare their progress by calculating the sum of squared differences in the number of…

Limiting Results with LIMIT and OFFSET

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Welcome to another detailed SQL tutorial! Today, we’ll be learning about two important SQL commands, LIMIT and OFFSET, which allows you to control how many rows you get from a database query. This is super useful when working with large datasets and you only want to see a small portion of the results. What is LIMIT? The LIMIT command in SQL helps you limit the number of rows returned by a query. This means if your table has hundreds of thousands of rows, you can use LIMIT it to display only a small set of those rows. Example: Imagine you…

Sorting Data with ORDER BY

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Welcome to today’s SQL course! In this post, we’ll learn how to sort data in SQL using the ORDER BY clause. Sorting helps us organize the results of our queries in a way that makes sense, whether we want to arrange data in ascending or descending order. Let’s start by breaking it down: What is ORDER BY? The ORDER BY clause in SQL is used to sort the results of a query. We can order the results based on one or more columns. By default, it sorts the data in ascending order (ASC), but we can also sort it in…

Filtering Data with WHERE Clauses

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In SQL, the WHERE clause helps us filter records that match certain conditions. Imagine you’re searching for something in a big box of toys, but you only want the red ones. The WHERE clause is like telling SQL to only give you the red toys. You can use different conditions (like equal to, greater than, or less than) to filter data in many ways. Structure of a WHERE Clause: The basic structure of the WHERE clause looks like this: Common Comparison Operators Here are some common comparison operators you can use in the WHERE clause: Examples of WHERE Clause Usage:…

Basic SELECT Queries

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Welcome to the world of SQL! Today, we’ll start learning how to use the basic SELECT query. SELECT is one of the most important commands in SQL because it allows you to retrieve or “select” data from a database. Think of a database like a giant bookshelf full of books, and each book contains information. The SELECT query is like the librarian helping you find and read specific books. Let’s dive into this simple but powerful SQL command. What is the SELECT Query? The SELECT query allows you to pick certain pieces of information from a table in a database.…