LIKE and ILIKE in PostgreSQL: The Art of Pattern Matching

Introduction

Searching for exact text matches? That’s basic level stuff. What if you need to find all records with a column that starts with "Game" or perhaps contains "Thrones"? Welcome to the world of LIKE and ILIKE in PostgreSQL, where you can perform advanced pattern matching like a pro. Let’s dive into the nitty-gritty and get you acquainted with these powerful search tools.

Basic Syntax and Usage

The LIKE and ILIKE operators are mainly used in the WHERE clause of a SELECT statement to filter records based on pattern matching. LIKE is case-sensitive, while ILIKE is case-insensitive.

SELECT column1, column2, ...
FROM table_name
WHERE column_name LIKE pattern;

-- OR

SELECT column1, column2, ...
FROM table_name
WHERE column_name ILIKE pattern;

Special Characters

• %: Represents zero or more characters.
• _: Represents a single character.

Examples with tv_series Table

Find all TV series that start with "Game":

SELECT name
FROM tv_series
WHERE name LIKE 'Game%';

How about series names containing the word "The," irrespective of case?

SELECT name
FROM tv_series
WHERE name ILIKE '%the%';

Common Errors and Solutions

Error Message:

ERROR:  syntax error at or near "LIKE"

Cause:
You probably misplaced the LIKE or ILIKE keyword, or forgot to enclose the pattern in single quotes.

Solution:
Review your SQL syntax carefully. Patterns should be enclosed in single quotes.

Pro Tips

• ILIKE is PostgreSQL-specific and might not work in other SQL databases. Use it wisely if you plan to port your database.
• Case-insensitive matching generally requires more processing, so if you don’t need it, stick with LIKE
• To improve performance, especially in large tables, consider creating text search indexes. If your database contains a lot of text data, consider indexing to speed up LIKE and ILIKE queries, especially those with patterns that are not left-anchored.

There you go, a complete guide to LIKE and ILIKE in PostgreSQL. Want to learn more? Got a complex pattern-matching problem? Leave a comment below!