Among them: altering the back-end query (specifically by reconsidering the use of concatenation) or limiting user-supplied input to avoid bad-faith language. Here are a few examples: Use parameterized ...

Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement.

Normalized data giving you problems? Learn how to use the SQL subselect statement and handle your database like a pro!