PHP and MySQL for Dynamic Web Sites: Visual QuickPro Guide

SQL and MySQL Debugging Techniques

The most common SQL errors are caused by the following issues:

• Unbalanced use of quotation marks or parentheses

• Unescaped apostrophes in column values

• Misspelling a column name, table name, or function

• Placing a query’s clauses (WHERE, GROUP BY, ORDER BY, LIMIT) in the wrong order

  Furthermore, when using MySQL you can also run across the following:

• Unpredictable or inappropriate query results

• Inability to access the database

• Difficulty starting MySQL

When creating Web applications in PHP, the best way to determine the SQL or MySQL issue at hand is to use the mysql_error() function, as introduced in Chapter 6, “Using PHP and MySQL.” In the next sequence of steps, I’ll cover another method for solving SQL and MySQL mistakes. ...