The use of char in mysql

The CHAR data type is used to store fixed-length text data in MySQL, which can ensure data consistency and improve query performance. This type specifies the data length, between 0 and 255 characters, which is specified when the table is created and remains constant for all rows of the same column. For variable-length data, it is recommended to use the VARCHAR type.

The purpose of CHAR type in MySQL

The CHAR data type is a fixed-length character in MySQL Data type used to store fixed-length text data.

Usage:

CHAR data type is mainly used in the following scenarios:

• Storage fixed-length text data: ## The #CHAR type is suitable for storing text data that does not change in length, such as country codes, postal codes, or order numbers.
• Ensure consistency: Because the CHAR data type is fixed-length, it ensures that all rows in the database table are of consistent length, which helps simplify data sorting and retrieval.
• Improve query performance: For fixed-length data, the CHAR type has higher query performance than the VARCHAR type because MySQL can directly access the data without calculating the variable length.

Length:

Note:

The CHAR type may waste storage space because it will occupy the entire allocated space even if the actual length of the data is less than the specified length. .
• If the actual length of the data exceeds the specified length, MySQL will truncate the data.
• For variable-length data, it is recommended to use the VARCHAR type.

Example:

<code class="sql">CREATE TABLE customers (
  customer_id CHAR(10) NOT NULL,
  customer_name CHAR(50) NOT NULL,
  PRIMARY KEY (customer_id)
);</code>

customer_id column in the above table uses the CHAR(10) data type, which means that each customer IDs are stored as a fixed length of 10 characters.

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