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LIKE - (PostgreSQL Conditions)

In PostgreSQL, the LIKE operator is used in the WHERE clause to search for a specified pattern in a column. In this tutorial, you'll learn about the syntax, example, and use of the LIKE operator in PostgreSQL.

Syntax

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

SELECT column_name(s) FROM table_name WHERE column_name LIKE pattern;

The LIKE operator compares a column value with a pattern, which can contain special characters to match on different kinds of values. Here are a few examples of the special characters you can use in a LIKE pattern:

  • % (percent sign) - matches any string of zero or more characters.
  • _ (underscore) - matches any single character.
  • [...] - matches any one of the characters listed between the brackets.
  • [^...] - matches any character that is not listed between the brackets.

Example

Let's say we have a table called employees with the columns id, name, email, and phone. We can use the LIKE operator to search for employees based on their name or email using patterns:

-- Find all employees whose name starts with "Joh"
SELECT * FROM employees WHERE name LIKE 'Joh%';

-- Find all employees with an email address ending in "example.com"
SELECT * FROM employees WHERE email LIKE '%@example.com';

Both of these queries will return all employees that match the pattern specified in the LIKE operator.

Explanation

The LIKE operator is used to search for a pattern within a column's value. In the first example, we searched for all employees whose name starts with "Joh". The % character is used to match zero or more characters, so the pattern "Joh%" matches any name that starts with "Joh", followed by zero or more additional characters.

In the second example, we searched for all employees with an email address ending in "example.com". We used the % character again, but this time we put it at the beginning of the pattern to match any characters before "@example.com". This will match any email address that ends with "@example.com", regardless of the characters before it.

Use

The LIKE operator in PostgreSQL is used to search for patterns within a column. This is useful for finding data that matches a specific pattern, such as all employees whose name contains a certain substring, or all email addresses that end with a specific domain.

Important Points

  • The LIKE operator is case-sensitive in PostgreSQL, so be sure to use the correct capitalization when searching.
  • When using the % character in a pattern, be sure to put it in the correct location depending on the pattern you're trying to match.
  • The LIKE operator can be slow for large datasets, especially when using % at the beginning of a pattern, as it requires a full table scan.

Summary

In this tutorial, we covered the basics of the LIKE operator in PostgreSQL. We discussed the syntax, example, explanation, use, and important points of using the LIKE operator in PostgreSQL. With this knowledge, you can use the LIKE operator to search for patterns within columns and find the data you need in your PostgreSQL databases.

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