What does char mean in mysql?

In MySQL, the char data type represents fixed-length character data and can store immutable text. Its features include: 1. Fixed length, high storage efficiency; 2. Performance advantages, convenient for comparison and sorting; 3. Filling space to ensure length; 4. Suitable for short text and key fields; 5. The length is limited to 255, and storage is possible Redundant, character set limitations may exist.

The meaning of char in MySQL

char is a fixed-length character data type in MySQL, used for Stores immutable text data. Its length is specified when the table is created and cannot be changed.

Features:

• Fixed length: The char data type has a predefined length, regardless of the actual length of the input text.
• Storage efficiency: Due to its fixed length, char is more space-efficient than variable-length data types such as VARCHAR.
• Performance advantages: The char data type provides better performance when performing comparison and sorting operations because its fixed length simplifies processing.
• Padding: If the length of the input text is less than the specified length, MySQL will fill the remaining space with spaces.

Usage scenarios:

The char data type is suitable for storing the following types of data:

• Short and immutable Text, such as a name, code, or identifier.
• Fields that must be of a specific length to ensure data consistency, such as zip code.
• A field used as a primary key or unique key because its fixed length helps improve indexing efficiency.

Limitations:

• Length Limitation: The length limit of char is 255 characters, for longer text required Use other data types (such as TEXT).
• Storage redundancy: If the length of the input text is less than the specified length, the char data type reserves unused space, resulting in storage redundancy.
• Character set limitations: The char data type is limited by the underlying character set and may not be able to store some special characters or non-Latin letters.

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