PHP and MySQL for Dynamic Web Sites: Visual QuickPro Guide

Using LIKE and NOT LIKE

Using numbers, dates, and NULLs in conditionals is a straightforward process, but strings can be trickier. You can check for string equality with a query such as

SELECT * FROM users WHERE user_name = 'trout';

However, comparing strings in a more liberal manner requires extra operators and characters. If, for example, you wanted to match a person’s last name that could be Smith or Smiths or Smithson, you would need a more flexible conditional. This is where the LIKE and NOT LIKE terms come in. These are used—primarily with strings—in conjunction with two wildcard characters: the underscore (_), which matches a single character, and the percentage sign (%), which matches zero or more characters. In my last-name example, ...