In the early days of MySQL, the explicit JOIN keyword was not available and joining criteria was added under the WHERE clause. While explicit joins are preferable, even today MySQL developers may come across legacy instances of implicit join. In this video, Steve Perry demonstrates how each approach is performed using SQL SELECT statements. Novice developers will be able to recognize each approach and understand how they can be used to combine two or more tables.

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Steve Perry teaches database design, MySQL, and the web development stack at Palomar College near San Diego. He's worked in IT and software development since 1977, holds a Master's degree in Education with an emphasis on adult education and online training, and is the author of multiple O'Reilly titles, including Learning SQL For Oracle and Dynamic Web Design with PHP and MySQL.

Article image: Screen from "What is the difference between explicit and implicit JOINs in MySQL?" (source: O'Reilly).