The transactions needed to store information in the database require Structured Query Language (SQL) commands placed inside a PHP script.

Should a SQL statement contain an error, PHP will return a cryptic, incomprehensible warning message via the driver. In debugging, it has been helpful to echo out the offending queries.

How SQL Works SQL, the structured query language, is a programming language for communicating with databases.

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