SQL UNICODE()

The SQL UNICODE() function returns the Unicode value of the first character in a specified string.

The UNICODE() function is useful for handling Unicode text data and allows you to retrieve character codes to understand encoding, perform sorting, or filter data based on specific characters.

The UNICODE() function is supported by SQL Server, and similar functions exist in other databases.

In this tutorial, we will go through SQL UNICODE() String function, its syntax, and how to use this function in SQL statements for string operations, with the help of well detailed examples.

Syntax of SQL UNICODE() Function

The basic syntax of the SQL UNICODE() function is:

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UNICODE(string);

Each part of this syntax has a specific purpose:

  • string: The input string from which the Unicode code of the first character will be returned.

The UNICODE() function returns the Unicode integer value of the first character of the input string. If the string is empty, it returns NULL.

Setup for Examples: Creating the Database and Table

We’ll create a sample users table with fields username and country_code. Follow these steps using MySQL or any SQL environment to set up the data for the UNICODE() function examples.

1. First, create a new database called app_data:

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CREATE DATABASE app_data;

2. Select the app_data database to work with:

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USE app_data;

3. Create a table named users with the fields user_id, username, and country_code:

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CREATE TABLE users (
    user_id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50),
    country_code VARCHAR(5)
);

4. Insert sample data into the users table to use with the UNICODE() function examples:

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INSERT INTO users (username, country_code)
VALUES
('Alice', 'US'),
('#Bob', 'CA'),
('Charlie', 'GB'),
('David99', 'AU'),
('*Eve', 'NZ');

With this setup complete, you can run the UNICODE() function examples to test and view results in the users table.

Examples: Using UNICODE() in SQL Queries

We’ll go through examples demonstrating the UNICODE() function in SQL, using sample data from a users table with fields username and country_code.

1. Retrieving Unicode Value of the First Character in a Username

To get the Unicode value of the first character in each username:

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SELECT username, 
       UNICODE(username) AS unicode_value
FROM users;

This query returns the Unicode value of the first character in each username, useful for identifying and sorting characters.

2. Checking for Special Characters Using UNICODE()

To identify usernames that start with special characters (e.g., Unicode values below 65 for ASCII characters):

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SELECT username
FROM users
WHERE UNICODE(username) < 65;

This query selects usernames that start with a character that has a Unicode value less than 65, often indicating a special character.

3. Filtering Rows Based on Character Code Ranges

To select usernames that start with uppercase English letters (Unicode values from 65 to 90):

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SELECT username
FROM users
WHERE UNICODE(username) BETWEEN 65 AND 90;

This query retrieves usernames where the first character is an uppercase letter, based on the Unicode range for uppercase English letters.

4. Using UNICODE() with Conditional Formatting

To display a message based on whether the first character of country_code is a letter (e.g., Unicode between 65 and 122):

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SELECT country_code,
       CASE 
           WHEN UNICODE(country_code) BETWEEN 65 AND 122 THEN 'Starts with a letter'
           ELSE 'Does not start with a letter'
       END AS code_status
FROM users;

This query uses UNICODE() in a conditional format to check if the first character in country_code is a letter.

FAQs for SQL UNICODE()

1. What does the SQL UNICODE() function do?

The UNICODE() function returns the Unicode integer value of the first character in a specified string.

2. Can UNICODE() handle NULL values?

If the input string is NULL, UNICODE() returns NULL.

3. Is UNICODE() supported in all SQL databases?

UNICODE() is supported in SQL Server, but similar functions are available in other databases, like ASCII() in MySQL for ASCII characters.

4. What is the difference between UNICODE() and ASCII()?

UNICODE() returns the Unicode value, which includes a broader range of characters, while ASCII() only returns ASCII character codes (0-127).

5. Can UNICODE() be used with other string functions?

Yes, UNICODE() can be combined with functions like CHARINDEX() and SUBSTRING() for complex character operations.