Mastering MySQL for Emojis: A Guide to utf8mb4, Collations

In the ever-evolving landscape of web development, the need to support diverse and expressive content, such as emojis, has become paramount. Emojis bring a new dimension to communication, and incorporating them into your MySQL database requires careful consideration of character sets and collations.

What is UTF-8

UTF-8 is a variable-width character encoding that can represent every character in the Unicode character set. It assigns a unique code point to each character, including emojis. Emojis are represented by code points beyond the Basic Multilingual Plane (BMP), and UTF-8 supports these extended code points.

Character Sets:

A character set is a collection of characters with a specific encoding. It defines how individual characters are represented as binary data. In MySQL, common character sets include:

latin1: Supports Western European languages.
utf8: Supports a wide range of characters, but not emojis or characters outside the Basic Multilingual Plane (BMP).
utf8mb4: Supports the entire Unicode character set, including emojis and characters outside the BMP.

If you have ever encountered this error, this means you tried to save some characters in a column, that doesn't support saving these characters.

Caused by: java.sql.SQLException: Incorrect string value: '\xE2\x80\x8D\xEF\xB8\x8F...' for column 'comment' at row 1

Character Set: utf8mb4

MySQL's utf8mb4 character set is essential for storing emojis, as it supports a wider range of characters compared to the traditional utf8. Emojis are encoded using more than three bytes, and utf8mb4 allows for this extended character encoding.

When creating a table, set the character set to utf8mb4 for columns that will store emojis:

CREATE TABLE my_table (
    emoji_column VARCHAR(255) CHARACTER SET utf8mb4,
    -- other columns
);

Emojis are UTF8 chars, but mysql utf8 charset doesn't have full support for emojis, so you need utf8mb4

COLLATE: utf8mb4_unicode_ci

Collation refers to the rules used for comparing and sorting characters in a character set. For utf8mb4, using the collation utf8mb4_unicode_ci is recommended. Let's break down its components:

utf8mb4: Specifies the character set.
unicode: Indicates that the collation follows Unicode sorting rules.
ci (case-insensitive): Denotes that the comparison is case-insensitive.

Understanding COLLATE Options:

MySQL supports various collations, each serving different linguistic and case sensitivity needs. Here's a brief overview:

a. Case Sensitivity:

ci (case-insensitive): Ignores case differences in comparisons.
cs (case-sensitive): Considers case differences in comparisons.

b. Accent Sensitivity:

ai (accent-insensitive): Ignores accent differences in comparisons.
as (accent-sensitive): Considers accent differences in comparisons.

You can run SHOW CHARACTER SET to see the list of character sets supported

mysql> SHOW CHARACTER SET;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_general_ci  |      4 |

You can run SHOW COLLATION LIKE 'utf8mb4%' to see the list of collations available.

mysql> SHOW COLLATION LIKE 'utf8mb4%';
+------------------------+---------+-----+---------+----------+---------+
| Collation              | Charset | Id  | Default | Compiled | Sortlen |
+------------------------+---------+-----+---------+----------+---------+
| utf8mb4_general_ci     | utf8mb4 |  45 | Yes     | Yes      |       1 |
| utf8mb4_bin            | utf8mb4 |  46 |         | Yes      |       1 |
| utf8mb4_unicode_ci     | utf8mb4 | 224 |         | Yes      |       8 |
| utf8mb4_icelandic_ci   | utf8mb4 | 225 |         | Yes      |       8 |
| utf8mb4_latvian_ci     | utf8mb4 | 226 |         | Yes      |       8 |
| utf8mb4_romanian_ci    | utf8mb4 | 227 |         | Yes      |       8 |

The main difference between utf8mb4_general_ci and utf8mb4_unicode_ci lies in the way they handle sorting and comparison of characters, particularly when it comes to non-European languages and characters with diacritics (accents). Let's explore each collation:

Performance vs. Precision:
- If you prioritize performance and are working with a diverse range of data but don't need language-specific sorting, utf8mb4_general_ci might be more suitable.
Accurate Language Sorting:
- If you need more accurate language-specific sorting, especially for non-European languages, or if you're dealing with complex linguistic requirements, utf8mb4_unicode_ci is a better choice.
General collations use simpler sorting rules, which may result in faster performance for certain operations.

CREATE TABLE example_table (
    id INT PRIMARY KEY,
    name VARCHAR(50)
);

When we don't specify the charset and collation, mysql applies the default values, you can check with show create table command

mysql> show create table example_table;
+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table         | Create Table                                                                                                                                           |
+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
| example_table | CREATE TABLE `example_table` (
  `id` int(11) NOT NULL,
  `name` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SHOW COLLATION LIKE 'latin1%';
+-------------------+---------+----+---------+----------+---------+
| Collation         | Charset | Id | Default | Compiled | Sortlen |
+-------------------+---------+----+---------+----------+---------+
| latin1_german1_ci | latin1  |  5 |         | Yes      |       1 |
| latin1_swedish_ci | latin1  |  8 | Yes     | Yes      |       1 |
| latin1_danish_ci  | latin1  | 15 |         | Yes      |       1 |
| latin1_german2_ci | latin1  | 31 |         | Yes      |       2 |
| latin1_bin        | latin1  | 47 |         | Yes      |       1 |
| latin1_general_ci | latin1  | 48 |         | Yes      |       1 |
| latin1_general_cs | latin1  | 49 |         | Yes      |       1 |
| latin1_spanish_ci | latin1  | 94 |         | Yes      |       1 |
+-------------------+---------+----+---------+----------+---------+
8 rows in set (0.00 sec)

Let's see the case sensitive and insensitive with an example.

First, we will create a table, We then insert some data into the table, including names with varying cases. Finally, we perform a case-insensitive comparison in the SELECT statement, searching for rows where the name is equal to 'APPLE'. The result will include the row with 'apple' because the comparison is insensitive to the case differences.

-- Create a table with a case-insensitive collation
CREATE TABLE example_table (
    id INT PRIMARY KEY,
    name VARCHAR(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci
);

-- Insert some data into the table
INSERT INTO example_table (id, name) VALUES
(1, 'apple'),
(2, 'Banana'),
(3, 'Orange'),
(4, 'cherry');

-- Perform case-insensitive comparisons
SELECT * FROM example_table WHERE name = 'APPLE';
+----+-------+
| id | name  |
+----+-------+
|  1 | apple |
+----+-------+

Now we drop the table and create a new one with case-sensitive collation.

CREATE TABLE example_table (
    id INT PRIMARY KEY,
        name VARCHAR(50) CHARACTER SET latin1 COLLATE latin1_general_cs
);
-- Insert some data into the table
INSERT INTO example_table (id, name) VALUES
(1, 'apple'),
(2, 'Banana'),
(3, 'Orange'),
(4, 'cherry');

-- Perform case-insensitive comparisons
SELECT * FROM example_table WHERE name = 'APPLE';

Empty set (0.01 sec)

In this example we don't get any result when we search for APPLE, but we get the results only when we search for apple

SELECT * FROM example_table WHERE name = 'apple';
+----+-------+
| id | name  |
+----+-------+
|  1 | apple |
+----+-------+
1 row in set (0.01 sec)

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Storing emojis in MySQL table