Episode 19 - Leetcode SQL | Sorting and Grouping | Number of unique subjects taught by each teacher 

Episode 19 - Leetcode SQL | Sorting and Grouping | Number of unique subjects taught by each teacher
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In Episode 19 of our Leetcode SQL series, we will explore essential SQL techniques, focusing on sorting and grouping data. This episode aims to help you understand how to effectively use these concepts to solve real-world problems, specifically by determining the number of unique subjects taught by each teacher.
What You'll Learn:
Sorting Data 📊: We will start by understanding how to sort data using the ORDER BY clause. Sorting helps in organizing data in a specific order, which is crucial for better readability and further data manipulation.
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Grouping Data 👥: Next, we'll dive into the GROUP BY clause, which is used to group rows that have the same values in specified columns into summary rows. This is particularly useful for aggregating data and is a fundamental operation in SQL.
Counting Unique Values 🔢: We'll then move on to using the COUNT function in conjunction with DISTINCT to count unique values in a dataset. This is essential for answering questions like "How many unique subjects does each teacher teach?"
Practical Example:
To illustrate these concepts, we'll work through a Leetcode problem that requires us to find the number of unique subjects taught by each teacher. We'll write a SQL query that:
Groups the data by the teacher's name.
Counts the distinct subjects for each teacher.
Sorts the results for better readability.
Step-by-Step Approach:
Step 1: Write a basic SELECT query to fetch the necessary columns (teacher's name and subject).
Step 2: Apply the GROUP BY clause to group the data by the teacher's name.
Step 3: Use the COUNT (DISTINCT subject) function to count the unique subjects for each teacher.
Step 4: Add the ORDER BY clause to sort the results, if needed.
By the end of this video, you will have a solid understanding of how to use sorting and grouping in SQL to analyze data effectively. This knowledge will not only help you solve this specific Leetcode problem but also equip you with skills applicable to a wide range of data manipulation tasks in SQL.
Join us for this in-depth exploration and take your SQL skills to the next level! 🚀
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