PostgreSQL NORMALIZE() String Function

PostgreSQL NORMALIZE() String Function

The PostgreSQL NORMALIZE() function is used to convert a string to a specified Unicode normalization form. This function is essential for ensuring that text data is stored in a consistent format, which is important for accurate text comparison and sorting.

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Syntax

NORMALIZE(string, form)

The NORMALIZE() function has the following components:

• string: The string to be normalized.
• form: The Unicode normalization form to be applied. Valid forms include 'NFC', 'NFD', 'NFKC', and 'NFKD'.

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Example PostgreSQL NORMALIZE() Queries

Let's look at some examples of PostgreSQL NORMALIZE() function queries:

1. Basic NORMALIZE() Example

SELECT NORMALIZE('Å', 'NFC') AS normalized_string;

This query normalizes the string 'Å' to its NFC (Normalization Form C) equivalent.

2. NORMALIZE() to NFD

SELECT NORMALIZE('Å', 'NFD') AS normalized_string;

This query normalizes the string 'Å' to its NFD (Normalization Form D) equivalent.

3. NORMALIZE() with Column Values

SELECT id, name, NORMALIZE(name, 'NFC') AS normalized_name
FROM users;

This query retrieves the id, name, and the NFC-normalized version of the name for each row in the users table.

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Full Example

Let's go through a complete example that includes creating a table, inserting data, and using the NORMALIZE() function to ensure consistent text data storage.

Step 1: Creating a Table

This step involves creating a new table named users to store user data.

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    name TEXT
);

In this example, we create a table named users with columns for id and name.

Step 2: Inserting Data into the Table

This step involves inserting some sample data into the users table.

INSERT INTO users (name)
VALUES ('Åsa'),
       ('Øyvind'),
       ('Ægir');

Here, we insert data into the users table.

Step 3: Using the NORMALIZE() Function

This step involves using the NORMALIZE() function to ensure consistent text data storage in the users table.

Basic NORMALIZE()

SELECT NORMALIZE('Å', 'NFC') AS normalized_string;

This query normalizes the string 'Å' to the NFC (Normalization Form C) form.

NORMALIZE() to NFD

SELECT NORMALIZE('Å', 'NFD') AS normalized_string;

This query normalizes the string 'Å' to the NFD (Normalization Form D) form.

NORMALIZE() with Column Values

SELECT id, name, NORMALIZE(name, 'NFC') AS normalized_name
FROM users;

This query normalizes the values in the 'name' column of the 'users' table to the NFC form.

These queries demonstrate how to use the NORMALIZE() function to ensure consistent text data storage in the users table, including basic usage and handling different normalization forms.

Conclusion

The PostgreSQL NORMALIZE() function is a fundamental tool for ensuring that text data is stored in a consistent format by converting strings to a specified Unicode normalization form. Understanding how to use the NORMALIZE() function and its syntax is essential for effective text data manipulation and storage in PostgreSQL databases.