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
Main Data Types
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
Lecture 13: Sorting Your Results with ORDER BY
This lecture covers the ORDER BY clause for sorting query results. When you use a `SELECT` statement, the database returns the rows in whatever order… Read More »Lecture 13: Sorting Your Results with ORDER BY
Lecture 12: Deleting Data with DELETE
This lecture covers the DELETE command to remove data. We have now covered Create, Read, and Update. The final core operation is Delete. The DELETE command is used… Read More »Lecture 12: Deleting Data with DELETE
Lecture 11: Updating Existing Data with UPDATE
This lecture covers the UPDATE command to modify existing data. So far, we have learned how to create data (`INSERT`) and read it (`SELECT`). These… Read More »Lecture 11: Updating Existing Data with UPDATE
Lecture 10: Mini-Project! Digital Address Book
This lecture concludes the digital address book mini-project, focusing on querying. Welcome to the second part of our mini-project. We have successfully created and populated… Read More »Lecture 10: Mini-Project! Digital Address Book