What does the "%" symbol represent in a SQL regular expression pattern?

The "%" symbol in a SQL regular expression pattern is a wildcard character that matches any sequence of zero or more characters.

Here's a step-by-step explanation:

1. SQL uses regular expression patterns for matching and manipulating strings.

2. In SQL, the "%" symbol is used as a wildcard character in these patterns.

3. When used in a pattern, the "%" symbol can match any sequence of characters, including an empty string.

4. For example, the pattern "%abc%" would match any string that contains "abc" anywhere in it. This could include "abc", "123abc", "abc123", "123abc123", and so on.

5. Similarly, the pattern "a%b" would match any string that starts with "a", ends with "b", and has zero or more characters in between. This could include "ab", "acb", "a123b", and so on.

6. The "%" symbol can be used multiple times in a pattern, and can be combined with other characters and wildcards to create complex matching rules.