Analysis of the difference between char and varchar in MySQL

Char fixed length, so the processing speed is much faster than varchar, but to the cost of storage space, so the storage is not small, but the speed of the requirements can use the char type, conversely, can be used to instantiate the varchar type

Jian Yi:

The MyISAM storage engine recommends using fixed-length, data columns instead of variable-length data columns.
The memory storage engine is currently using fixed data row storage, so it doesn't matter whether you use char varchar columns,
InnoDB storage engine built to use varchar type

Analysis of the difference between char and varchar in MySQL