📘 Section 1: Introduction to MySQL LIKE

The MySQL LIKE operator is used in a WHERE clause to find rows where a text column matches a pattern. The pattern can include special wildcards that control how matching works.

Two wildcards you’ll use

  • % — matches any number of characters (including zero). Example: 'data%', '%data%'.
  • _ — matches exactly one character. Example: 'A_C' matches ABC, A3C.

Basic syntax

SELECT column_list
FROM table_name
WHERE column_name LIKE pattern;

The pattern is a quoted string (e.g., '%sql%') that may include % or _.

Quick examples

-- Contains "mysql" anywhere
WHERE title LIKE '%mysql%';

-- Starts with "sql"
WHERE title LIKE 'sql%';

-- Ends with ".com"
WHERE url LIKE '%.com';

-- Exactly one character between A and C (A?C)
WHERE code LIKE 'A_C';

Common patterns at a glance

Goal Pattern Example match
Contains word %like% “mysql like query”
Starts with mysql% “mysql syntax”
Ends with %.pdf “notes.pdf”
Single-char wildcard A_C “ABC”, “A3C”, “A-C”
Tip: LIKE is usually affected by your column’s collation. In most default collations (e.g., utf8mb4_general_ci) it’s case-insensitive; you can force case-sensitive checks with BINARY or a case-sensitive collation (covered later).
Heads-up: A leading wildcard (e.g., '%term') prevents normal index use and can be slow on big tables. We’ll cover performance later.

What is the LIKE Operator in MySQL?

Definition of LIKE Operator

The LIKE operator in MySQL is used to search for a specified pattern in a column. Unlike the = operator that only returns exact matches, the LIKE operator allows for partial matching, making it extremely useful for querying text-based data where the full value might not be known.

With the LIKE operator, you can easily find records that match a specific pattern or set of characters, making your SQL queries more flexible.

Basic Syntax of the LIKE Operator

The basic syntax of the LIKE operator in MySQL is as follows: 

SELECT column_name
FROM table_name
WHERE column_name LIKE pattern;

– column_name: The column in which the pattern will be searched.
– table_name: The name of the table where the column exists.
– pattern: The pattern you are looking for, which can include wildcard characters (e.g., % or _).

Use Cases of the LIKE Operator

The LIKE operator is extremely useful for situations where you are unsure of the full value you are searching for. Here are some common use cases:

  • Searching Customer Names: Find all customers whose names start with “Jo” (e.g., “John”, “Joan”).
  • Product Descriptions: Search for products with a certain keyword in their description, like “laptop”.
  • Location-based Queries: Retrieve all records from a specific city or area using a partial name match.

Example Query

Here is an example query using the LIKE operator to search for products that contain the word “phone” in their name: 

SELECT product_name
FROM products
WHERE product_name LIKE '%phone%';

This query will retrieve all product names that contain the word “phone”, such as “Smartphone”, “Phone Case”, etc.

Understanding Wildcards in MySQL

Wildcards in MySQL

Wildcards are special characters used in combination with the LIKE operator to perform pattern matching in SQL queries. They allow for more flexible searches, enabling you to search for partial matches, specific characters, or unknown portions of a string.

The two primary wildcards used with the LIKE operator are:

  • %: Matches zero or more characters.
  • _: Matches exactly one character.

Using LIKE with Wildcards

Here are some simple examples of how to use the LIKE operator with wildcards in MySQL:

  • Searching for names that start with a specific letter: 
    WHERE name LIKE 'A%';
  • Finding products that contain a specific word: 
    WHERE product_name LIKE '%book%';
  • Searching for names with a specific character in the second position: 
    WHERE name LIKE '_o%';

Advanced Use Cases for LIKE and Wildcards

Combining LIKE with Other Operators

The LIKE operator can be combined with other operators like AND, OR, and NOT to create more complex conditions in your queries. 

SELECT product_name 
FROM products
WHERE product_name LIKE 'A%' AND price > 100;

In this example, we combine the LIKE operator with the AND operator to find products whose names start with “A” and have a price greater than 100.

Handling Case Sensitivity with LIKE

MySQL’s LIKE operator can be case-sensitive depending on the collation of the column. By default, most MySQL collations are case-insensitive, but this can vary. To perform a case-sensitive search, you can use the COLLATE clause to specify the collation type. 

SELECT product_name 
FROM products 
WHERE product_name LIKE 'A%' COLLATE utf8_bin;

In this example, the query will be case-sensitive due to the utf8_bin collation.

Query Optimization Tips for LIKE

Using the LIKE operator with wildcards can sometimes lead to performance issues, especially when dealing with large datasets. Here are some tips to optimize your queries:

  • Avoid using leading wildcards: Using wildcards at the beginning of the pattern (e.g., ‘%phone’) prevents MySQL from using indexes efficiently.
  • Indexing: If possible, index columns that are frequently queried with the LIKE operator.
  • Use Full-Text Search: For large text-based searches, consider using MySQL’s full-text indexing features.

Common Mistakes and How to Avoid Them

  • Forgetting wildcard placement: Ensure that wildcards are placed correctly in the pattern. For example, using '%book instead of 'book%' can lead to unexpected results.
  • Overuse of LIKE: Using the LIKE operator when an exact match (=) is more efficient can negatively impact performance.
  • Performance issues with large datasets: Using the LIKE operator on large datasets without indexing or optimization techniques can lead to slower query times.

Best Practices for Using LIKE and Wildcards

  • Use wildcards sparingly: Wildcards can slow down queries, so only use them when necessary.
  • Combine wildcards thoughtfully: Use combinations like 'A%' and '%book' to get more precise results.
  • Test on smaller datasets: Always test queries with LIKE on smaller datasets before scaling them to large tables to avoid performance issues.

Conclusion

Recap: Mastering the LIKE Operator and Wildcards

Mastering the LIKE operator and wildcards is key to achieving powerful and dynamic pattern matching in MySQL. By understanding and utilizing wildcards like % and _, you can create flexible search queries that meet your specific data retrieval needs.

Regular practice will help you improve your query writing skills, allowing you to efficiently write complex SQL queries. Experimenting with different wildcard patterns will refine your understanding and enhance your MySQL querying ability.

Further SQL Learning Resources

To continue enhancing your SQL skills, explore additional resources to deepen your understanding and explore advanced SQL topics. Check out these valuable SQL learning resources: SQL Learning Resources .

Call to Action: Take Your SQL Skills to the Next Level

Explore Additional SQL Tutorials and Real-World Practice

Now that you’ve mastered the LIKE operator and wildcards, it’s time to expand your knowledge and practice with more advanced SQL topics. The best way to improve your skills is through hands-on experience. Explore the following tutorials and practice on real-world datasets to take your SQL expertise to the next level:

These resources will guide you through complex SQL concepts and offer practical tips for real-world applications. Keep learning and refining your skills, and don’t forget to practice on real datasets to solidify your knowledge.

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