MySQL Wildcards

MySQL wildcards are special characters used in SQL queries to search for data that matches a specified pattern. They are particularly useful in LIKE statements for filtering results based on partial matches.

Key Concepts

• Wildcard Characters: There are two main wildcard characters used in MySQL:
  • % (percent sign): Represents zero or more characters.
  • _ (underscore): Represents a single character.
• Usage in Queries: Wildcards are used in conjunction with the LIKE operator in SQL queries to filter results based on patterns.

Examples

Using the % Wildcard

Example Query: Find all names that end with 'n':

SELECT * FROM employees WHERE name LIKE '%n';

This will return names like 'John', 'Ben', 'Karen', etc.

Example Query: Find all names that start with 'J':

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

This will return names like 'John', 'Jane', 'Jack', etc.

Using the _ Wildcard

Example Query: Find names that have 'a' in the second position:

SELECT * FROM employees WHERE name LIKE '_a%';

This will return names like 'Dan', 'Sam', etc.

Example Query: Find all names with exactly three characters, where the first character is 'A':

SELECT * FROM employees WHERE name LIKE 'A__';

This will return names like 'Ana', 'Amy', etc.

Summary

• Wildcards in MySQL allow for flexible and powerful pattern matching in queries.
• The % wildcard is used for multiple characters, while the _ wildcard is used for a single character.
• These wildcards enhance the ability to search and filter data effectively.

By mastering wildcards, you can significantly improve your ability to retrieve specific data from your MySQL databases!