Unleashing the Power of Pattern Operators in PostgreSQL

3 min readMar 11, 2024

Welcome to our exploration of pattern operators in PostgreSQL! In this blog post, we’ll dive deep into the world of pattern matching, uncovering the capabilities of various operators that PostgreSQL offers for this purpose. From the well-known ILIKE operator to the powerful regular expression-based operators, we’ll cover it all.

Understanding Pattern Operators

Pattern operators in PostgreSQL are essential for performing advanced searches and manipulations on string data. They allow you to define patterns and match them against strings stored in your database tables. Let’s delve into some of the most commonly used pattern operators:

ILIKE Operator

The ILIKE operator is designed for case-insensitive pattern matching. It’s particularly useful when you need to search for strings without considering their case. The syntax is simple:

column_name ILIKE pattern;

Where % matches any sequence of characters and _ matches any single character.

LIKE Operator

Similar to ILIKE, the LIKE operator performs pattern matching, but it’s case-sensitive. It uses wildcard characters % and _ for pattern matching.

column_name LIKE pattern;

SIMILAR TO Operator

The SIMILAR TO operator allows pattern matching using regular expressions, providing more flexibility than ILIKE and LIKE. It’s particularly useful when you need more intricate pattern matching capabilities.

column_name SIMILAR TO pattern;

REGEXP_MATCHES Operator

For advanced pattern matching based on POSIX regular expressions, PostgreSQL offers the REGEXP_MATCHES function. This function returns all substrings matching a given pattern.

REGEXP_MATCHES(string, pattern);

POSITION Operator

The POSITION operator finds the position of a substring within a string. It’s useful when you need to determine the position of a specific pattern within a string.

POSITION(substring IN string);

Examples of Pattern Operators

Let’s illustrate the usage of these pattern operators with some examples:

Example 1: Using ILIKE Operator

Suppose we want to find all products whose names contain the word “apple”, ignoring case:

SELECT
    product_name
FROM
    products
WHERE
    product_name ILIKE '%apple%';

Example 2: Using LIKE Operator

Suppose we want to find all users whose usernames start with “user”:

SELECT
    username
FROM
    users
WHERE
    username LIKE 'user%';

Example 3: Using SIMILAR TO Operator

Suppose we want to find all emails that follow a specific pattern:

SELECT
    email_address
FROM
    users
WHERE
    email_address SIMILAR TO '[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}';

Example 4: Using REGEXP_MATCHES Operator

Suppose we want to extract all words starting with the letter “P” from a given text:

SELECT
    (REGEXP_MATCHES(text_column, '\mP\w+', 'g'))[1]
FROM
    text_table;

Example 5: Using POSITION Operator

Suppose we want to find the position of the first occurrence of the word “world” in a text:

SELECT
    POSITION('world' IN text_column) AS position_of_world
FROM
    text_table;

Conclusion

Pattern operators in PostgreSQL provide powerful tools for performing advanced pattern matching and manipulation operations on string data. Whether you need simple case-insensitive matching, case-sensitive matching, or complex regular expression-based matching, PostgreSQL has you covered. By mastering these operators, you can unlock the full potential of pattern matching in your database queries.

Stay tuned for more insights and tips on mastering PostgreSQL and other powerful database technologies!