Lecture 23: Linking Tables with Foreign Keys
This lecture introduces the concept of Foreign Keys. If the primary key is the anchor of a table, the foreign key is the chain that links it… Read More »Lecture 23: Linking Tables with Foreign Keys
Lecture 23: Linking Tables with Foreign Keys
Lecture 22: The Importance of Primary Keys
This lecture introduces the concept of Primary Keys. Welcome to Part 3 of our series. So far, we have worked with single tables. But the… Read More »Lecture 22: The Importance of Primary Keys
Lecture 21: Mini-Project – Student Grades Part 2
This lecture concludes the student grades mini-project with data analysis. Welcome back. In the last lecture, we created our `Grades` table and filled it with… Read More »Lecture 21: Mini-Project – Student Grades Part 2
Lecture 20: Mini-Project – Student Grades Part 1
This lecture begins a mini-project to analyze student grades. Let’s begin our second mini-project. This time, we will create a database to store student grades… Read More »Lecture 20: Mini-Project – Student Grades Part 1
Lecture 19: Grouping Data with GROUP BY
This lecture introduces the GROUP BY clause. So far, our aggregate functions have given us one single result for the entire table (or a filtered… Read More »Lecture 19: Grouping Data with GROUP BY
Lecture 18 – Finding Minimum and Maximum Values
This lecture covers the MIN() and MAX() aggregate functions. To round out our introduction to aggregate functions, we will look at two simple but very… Read More »Lecture 18 – Finding Minimum and Maximum Values
Learn Databases: Lecture 17 – SUM and AVG
This lecture covers the SUM() and AVG() aggregate functions. After counting rows, the next most common summary tasks are calculating the total and the average… Read More »Learn Databases: Lecture 17 – SUM and AVG
Lecture 16 – Counting Rows with COUNT
This lecture introduces the COUNT() aggregate function. Welcome to the world of aggregate functions. An aggregate function performs a calculation on a set of rows and… Read More »Lecture 16 – Counting Rows with COUNT
Lecture 15: Finding Unique Values with DISTINCT
This lecture covers the DISTINCT keyword to find unique values. Often, a column in your table will contain duplicate values. For example, in our `Contacts`… Read More »Lecture 15: Finding Unique Values with DISTINCT
Lecture 14: Limiting Your Results with LIMIT
This lecture covers the LIMIT clause to restrict the number of rows returned. Sometimes your queries can return thousands or even millions of rows. Displaying… Read More »Lecture 14: Limiting Your Results with LIMIT