In SQL, pattern matching allows you to search for specific patterns within text data. One common way to perform pattern matching is by using wildcard characters. Wildcard characters are special characters that can represent unknown values or a range of characters in a search pattern.

In SQL, there are two main wildcard characters that can be used for pattern matching:

1. % (percentage sign): This wildcard character represents any sequence of characters, including zero characters.

2. _ (underscore): This wildcard character represents a single character.

Let’s explore some examples of how to use wildcard characters for pattern matching in SQL.

Example 1: Using % as a Wildcard

Suppose we have a table called users with a name column. We want to retrieve all users whose names start with “J”. We can use the % wildcard character to achieve this:

SELECT * FROM users WHERE name LIKE 'J%';

This query will return all rows from the users table where the name starts with “J”.

Example 2: Using _ as a Wildcard

Suppose we want to retrieve all users whose names have exactly three characters, where the first character is “J” and the third character is “n”. We can use the _ wildcard character to represent any single character:

SELECT * FROM users WHERE name LIKE 'J_n';

This query will return all rows from the users table where the name has exactly three characters, starting with “J” and ending with “n”.

Conclusion

Pattern matching with wildcard characters is a powerful feature in SQL that allows you to search for specific patterns within text data. By using % and _ wildcard characters, you can perform flexible and targeted searches in SQL queries. Remember to use these wildcard characters in conjunction with the LIKE keyword to perform pattern matching operations in your SQL statements.

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