Handling Character Encodings and Format Mismatches

Imagine that our OnlineStore is expanding worldwide. We begin receiving product information from Japan, France, and Germany suppliers. Suddenly, names such as Éclair or Übersetzung appear in our database as Ãclair, Übersetzung, or even ??????. In another case, we receive a CSV file with sales data in the DD/MM/YYYY format, while our system expects YYYY-MM-DD. The result: all our import scripts fail.

By the end of this lesson, we’ll be able to:

• Understand character encodings and why they’re so important for data integrity.

• Identify common character encoding issues, like those strange symbols, and know how to fix them in MySQL.

• Recognize various data format mismatches during data import and export operations.

• Learn effective techniques and MySQL commands to handle these format mismatches, ensuring our data stays accurate and usable.

Let’s dive in and learn how to make our data flow seamlessly, no matter where it comes from or what language it’s in!

Understanding character encodings

Ever seen text on a website or in a database that looks like a jumble of random symbols, like “helloâ€?instead of “hello”? This is often a character encoding issue, sometimes called mojibake. Character encodings are fundamental to storing and displaying text data correctly. If we get them wrong, we risk data corruption, difficulties supporting multiple languages in our applications (like our global OnlineStore), and search functionalities not working as expected. For instance, if a customer searches for café, but it’s stored as cafe or caf?, they might not find the product they’re looking for. Correct character encoding is crucial for data integrity and a good user experience.

At its core, a character encoding system tells the computer how to interpret raw binary data (0s and 1s) as actual text characters. A character set is a collection of characters (like letters, numbers, and symbols). An encoding is the method used to represent these characters in bytes. For example, ASCII was an early character set, mostly for English characters. ISO-8859-1 (also known as Latin1) extended it for Western European languages.

However, Unicode was developed to support all languages and a vast array of symbols (like emojis 👍). UTF-8 is the most common Unicode encoding used on the web and in modern applications. It’s a variable-width encoding that uses one to four bytes to represent each character. For MySQL, it’s highly recommended to use utf8mb4, which is a UTF-8 encoding that supports the full Unicode character set, including emojis and less common symbols that utf8 (an older MySQL-specific UTF-8 implementation limited to 3 bytes) might not handle.

A collation is a set of rules that define how to compare and sort character strings. For example, a collation might specify whether A and a are treated the same for sorting (_ci for case-insensitive) or different (_cs for case-sensitive), or how characters with accents are sorted. Each character set has a default collation and several other compatible collations. For utf8mb4, a common and good general-purpose collation is utf8mb4_unicode_ci.

Character encodings in MySQL

MySQL can handle character sets and collations at several levels:

1. Server level: The server’s ...