MySQL Cookbook, 2nd Edition

Pattern Matching with SQL Patterns

Problem

You want to perform a pattern match rather than a literal comparison.

Solution

Use the LIKE operator and an SQL pattern, described in this section. Or use a regular-expression pattern match, described in Pattern Matching with Regular Expressions.

Discussion

Patterns are strings that contain special characters. These are known as metacharacters because they stand for something other than themselves. MySQL provides two kinds of pattern matching. One is based on SQL patterns and the other on regular expressions. SQL patterns are more standard among different database systems, but regular expressions are more powerful. The two kinds of pattern match uses different operators and different sets of metacharacters. This section describes SQL patterns. Pattern Matching with Regular Expressions describes regular expressions.

The example here uses a table named metal that contains the following rows:

+----------+
| name     |
+----------+
| copper   |
| gold     |
| iron     |
| lead     |
| mercury  |
| platinum |
| silver   |
| tin      |
+----------+

SQL pattern matching uses the LIKE and NOT LIKE operators rather than = and != to perform matching against a pattern string. Patterns may contain two special metacharacters: _ matches any single character, and % matches any sequence of characters, including the empty string. You can use these characters to create patterns that match a variety of values:

• Strings that begin with a particular substring:

  mysql>SELECT name FROM metal WHERE ...