SQL: Grouping, joins and Injections

Learn how to group tables using different joins and safeguard the database from SQL injections.

Let’s finish our introduction to SQL by learning ways to aggregate data from multiple records and even multiple tables in our queries.


We can aggregate multiple records to get statistical analysis. We do this by using the group functions. The most common of them is count().

Here’s how we can get the count of all the plays from our database:

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