Fix Unknown collation utf8mb4_0900_ai_ci in MySQL: Best Solution

This tutorial aims to guide you on how to Fix Unknown collation utf8mb4_0900_ai_ci in MySQL. We’ll explore the reasons behind this error and its significance, followed by a step-by-step guide to resolving it. The Fix Unknown collation utf8mb4_0900_ai_ci in MySQL error is a common issue when working with different versions of MySQL.

When you encounter this "Unknown collation" error, it’s often related to your MySQL version. If you’re using a MySQL version older than 8.0.1, your MySQL server might not support the utf8mb4_0900_ai_ci collation. Therefore, knowing how to Fix Unknown collation utf8mb4_0900_ai_ci in MySQL is important.

What is utf8mb4_0900_ai_ci in MySQL?

utf8mb4_0900_ai_ci is a character set collation used in MySQL databases. It’s based on the Unicode Collation Algorithm (UCA) version 9.0.0 and was introduced in MySQL version 8.0.1.

The "ai" parameter stands for "accent insensitive," meaning that the collation disregards differences in accents during comparisons. Similarly, "ci" represents "case insensitive," indicating that the collation ignores differences in case (uppercase vs. lowercase). This collation is designed for more accurate and culturally sensitive string comparisons. This is a critical point to understand when you’re trying to Fix Unknown collation utf8mb4_0900_ai_ci in MySQL.

Now, let’s delve into the steps to fix the "Unknown collation" error in MySQL.

How To Fix Unknown collation utf8mb4_0900_ai_ci in MySQL?

As mentioned earlier, this error typically arises if your MySQL version is older than 8.0.1. The initial solution involves modifying your database backup file.

To resolve this issue, follow these steps:

First, create a backup of your MySQL database server using tools like mysqldump. This is crucial in case anything goes wrong during the modification process.

Next, open the backup file (usually a .sql file) with a text editor of your choice, such as vi editor, Notepad++, or Sublime Text.

Within the file, search for the following line:

ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

Replace this entire line with the following:

ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci;

By changing utf8mb4 to utf8 and utf8mb4_0900_ai_ci to utf8_general_ci, you’re effectively using an older, more widely compatible character set and collation. utf8 is an older version that works well with MySQL versions prior to 8.0.1.

After making the changes, save and close the file.

You can also automate this replacement using command-line tools like sed. Run the following commands in your terminal:

# sed -i 's/utf8mb4_0900_ai_ci/utf8_general_ci/g' backup.sql
# sed -i 's/CHARSET=utf8mb4/CHARSET=utf8/g' backup.sql

These commands will replace all occurrences of utf8mb4_0900_ai_ci with utf8_general_ci and CHARSET=utf8mb4 with CHARSET=utf8 within the backup.sql file.

Finally, restore the modified backup.sql file to your MySQL server.

That’s it! By following these steps, you should be able to resolve the "Unknown collation" error.

Note: This approach allows you to change and fix all unknown collations in older MySQL versions.

Alternative Solutions to Fix Unknown collation utf8mb4_0900_ai_ci in MySQL

While the above method works, it involves modifying the backup file. Here are two alternative solutions that might be more suitable in certain situations:

1. Upgrade Your MySQL Server:

The most straightforward and recommended solution is to upgrade your MySQL server to version 8.0.1 or later. This version natively supports the utf8mb4_0900_ai_ci collation, eliminating the error altogether.

• Explanation: Upgrading ensures that your server supports the latest features and collations, improving compatibility and potentially enhancing performance.

• How to Upgrade: The upgrade process varies depending on your operating system and current MySQL version. Refer to the official MySQL documentation for detailed instructions: https://dev.mysql.com/doc/refman/8.0/en/upgrading.html

2. Modify the Connection Collation:

Instead of changing the database or table collation, you can adjust the collation used by your database connection. This can be done through your application’s connection string or by setting the collation within your MySQL client.

• Explanation: This approach avoids altering the database schema and allows you to handle the collation issue at the application level.

• Code Example (PHP):

  <?php
  $servername = "localhost";
  $username = "your_username";
  $password = "your_password";
  $database = "your_database";
  
  // Create connection
  $conn = new mysqli($servername, $username, $password, $database);
  
  // Check connection
  if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
  }
  
  // Set connection collation
  $conn->query("SET NAMES 'utf8' COLLATE 'utf8_general_ci'");
  
  // Perform database operations
  $sql = "SELECT * FROM your_table";
  $result = $conn->query($sql);
  
  if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
      echo "id: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }
  } else {
    echo "0 results";
  }
  
  $conn->close();
  ?>

  In this PHP example, the line $conn->query("SET NAMES 'utf8' COLLATE 'utf8_general_ci'"); sets the connection collation to utf8_general_ci before executing any queries.

• Code Example (Python):

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="yourdatabase",
  charset='utf8',
  collation='utf8_general_ci'
)

mycursor = mydb.cursor()

mycursor.execute("SELECT * FROM yourtable")

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

This Python example sets the charset and collation in the connection string itself, ensuring that the connection uses utf8_general_ci.

These two alternative methods offer ways to address the "Unknown collation" error without directly modifying the database backup file. Choosing the best approach depends on your specific environment and requirements.

Conclusion

In summary, you’ve learned how to Fix Unknown collation utf8mb4_0900_ai_ci Error in MySQL. This error commonly occurs in older MySQL versions before 8.0.1. While using utf8 instead of utf8mb4 is a viable solution, upgrading your MySQL server or modifying the connection collation are also excellent alternatives. Remember to always back up your data before making any changes to your database. Understanding these methods will equip you to handle collation issues effectively in your MySQL environment.

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