Sqlite String Not Like

5 min read Oct 12, 2024

Understanding "LIKE" and "NOT LIKE" in SQLite

SQLite is a widely-used embedded database system, known for its simplicity and efficiency. When working with SQLite, you'll often need to query your data using various comparison operators. One of the most common and powerful operators is LIKE, which allows you to perform pattern matching on string data.

But what about situations where you need to find data that doesn't match a particular pattern? This is where the NOT LIKE operator comes in.

What is the "NOT LIKE" Operator?

The NOT LIKE operator in SQLite is used to select data that doesn't match a specified pattern. It works in conjunction with wildcards, such as the percent sign (%) and the underscore (_), to create flexible search criteria.

Here's a breakdown of how it works:

% (Percent Sign): Matches any sequence of zero or more characters.
_ (Underscore): Matches any single character.

Practical Examples of "NOT LIKE" in SQLite

Let's look at some practical examples to illustrate how to use the NOT LIKE operator in your SQLite queries:

1. Finding Records that Don't Start With a Specific String:

SELECT * FROM products WHERE name NOT LIKE 'A%';

This query will select all records from the products table where the name column doesn't begin with the letter 'A'.

2. Finding Records that Don't Contain a Specific String:

SELECT * FROM customers WHERE email NOT LIKE '%@gmail.com%';

This query will select all records from the customers table where the email column doesn't contain the string @gmail.com.

3. Finding Records that Don't Have a Specific Number of Characters:

SELECT * FROM orders WHERE order_id NOT LIKE '____';

This query will select all records from the orders table where the order_id column doesn't have exactly four characters.

4. Finding Records that Don't End With a Specific Extension:

SELECT * FROM files WHERE filename NOT LIKE '%.pdf';

This query will select all records from the files table where the filename column doesn't end with the .pdf extension.

Tips for Using "NOT LIKE" Effectively

Use Wildcards Strategically: The % and _ wildcards are powerful tools, but use them judiciously to avoid overly broad or ambiguous queries.
Escape Special Characters: If your search pattern includes special characters like % or _, you'll need to escape them using the backslash (\) character. For example:
```
SELECT * FROM items WHERE description NOT LIKE '%\%'; -- Finds items that don't contain the percent sign
```
Consider Alternatives: For some cases, using other SQLite operators like NOT IN or <> (not equals) may be more efficient than NOT LIKE.

Conclusion

The NOT LIKE operator in SQLite provides a powerful way to filter data based on patterns that you don't want to match. It's a versatile tool that can be used in many scenarios, making your SQLite queries more precise and effective.