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.
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'.Let's look at some examples of PostgreSQL NORMALIZE()
function queries:
SELECT NORMALIZE('Å', 'NFC') AS normalized_string;
This query normalizes the string 'Å' to its NFC (Normalization Form C) equivalent.
SELECT NORMALIZE('Å', 'NFD') AS normalized_string;
This query normalizes the string 'Å' to its NFD (Normalization Form D) equivalent.
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.
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.
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
.
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.
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.
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.