17 Aug 2017 Francisco Claria Referential Constraints and Foreign Keys in MySQL Foreign keys and referential constraints allow you to set relationships between tables and modify some of the database engine’s actions. This beginner’s guide explains referential integrity and foreign key use in MySQL. One of the most important aspects of database usage is being able to trust the information you store. Database engines provide several features that help you maintain the quality of your data, like defining required columns as NOT NULL and setting an exact data type for each column. Read more 6 Jul 2017 Francisco Claria An Introduction to Using SQL Aggregate Functions with JOINs Previously, we've discussed the use of SQL aggregate functions with the GROUP BY statement. Regular readers of the our blog will also remember our recent tutorial about JOINs. If you're a bit rusty on either subject, I encourage you to review them before continuing this article. That's because we will dig further into aggregate functions by pairing them with JOINs. This duo unleashes the full possibilities of SQL aggregate functions and allows us to perform computations on multiple tables in a single query. Read more 13 Jun 2017 Francisco Claria Learning JOINs With Real World SQL Examples The JOIN statement lets you work with data stored in multiple tables. In this article, I’ll walk you through the topic of JOIN clauses using real world SQL examples. Imagine if you could only work with one database table at a time. Fortunately, this isn’t anything we have to worry about. Once you learn the JOIN statement, you can start linking data together. In this article, I’ll use real world SQL examples that illustrate how we use JOINs, how each type of JOIN works, and when to use each type. Read more 10 Apr 2017 Francisco Claria Preventing Common SQL Mistakes Regardless of the engine you are using (SQL Server, MySQL, Oracle, etc.), you can prevent common errors and simplify the debugging process. This article will discuss some of the common SQL mistakes you’ll face and will help you correct them easily. One of the best ways to prevent the most common SQL mistakes is to keep your queries clear and readable. It’s very easy to forget the ideas behind your code! Read more