What is the difference between char and varchar in mysql

The differences between char and varchar in mysql are: 1. CHAR is fixed length, while VARCHAR is variable length; 2. CHAR storage and retrieval efficiency is high, while VARCHAR storage and retrieval efficiency is not high; 3. , CHAR takes up storage space, while VARCHAR can save storage space.

The operating system of this tutorial: windows10 system, mysql8.0.16 version, DELL G3 computer.

In MySQL, CHAR and VARCHAR are both types used to store character data, but there are some key differences between them.

1. Storage method: CHAR is fixed length, while VARCHAR is variable length. This means that CHAR reserves a fixed size of storage space for each character stored, while VARCHAR dynamically adjusts the storage space based on actual needs.

2. Storage efficiency: Since CHAR is of fixed length, storage and retrieval efficiency may be higher in some cases. This can eliminate some extra processing because the database doesn't need to think about how to split or merge the data at query time.

3. Storage space: Compared with CHAR, VARCHAR can save storage space because it only stores actual data and does not store additional spaces.

The following are some specific comparisons:

CHAR(n) Type used to store fixed-length strings, where n is a positive integer. If the length of the stored string is less than n, MySQL will use spaces to complete n characters at the end of the string. For example, CHAR(5) can store a string with a length of 1 to 5, and the storage space is 5 characters.

VARCHAR(n) Type used to store variable-length strings, where n is a positive integer. VARCHAR will allocate storage space according to the actual stored string length, and will not use spaces to complete the length. For example, VARCHAR(5) can store strings with a length of 1 to 5, and the storage space is allocated according to the actual string length.

When choosing the CHAR or VARCHAR type, you need to decide based on actual needs and data characteristics. If the length of the string is known to be essentially fixed and storage space is not a major consideration, CHAR may be more suitable. If string lengths vary widely and storage space is a concern, VARCHAR may be more appropriate.

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