MySQL中的enum类型有什么优点？

Question

刚开始用MYSQL，一直没注意到这个类型，它有什么优点？或者说如果存储内容都是短字符串的话，它跟varchar有何区别？

Answer 1

For example, the following two fields:

name varchar(50) , 
sex  enum('male' , 'female' , 'both' , 'unknow')

The name field can be inserted into any string. name 字段可以插入任意字符串。

sex 字段只允许插入 male , female , both , unknow 中的其中之一，不在范围内的值会报错。

enum 相比较 varchar

The sex field only allows one of male, female, both, unknown to be inserted. Values ​​that are not within the range will report an error.

enum is more standardized compared to varchar, and you can also limit it in the program. 🎜 🎜For performance comparison, I have to wait for the experts to answer...🎜

Answer 2

The advantage of Enum is that the value can be within several value ranges

Answer 3

The speed of querying string and enum is almost the same. It is logical to use enum or set. . .

Answer 4

The underlying storage method of enum is integer type
For example, such a field
sex enum('male', 'female', 'both', 'unknow')
When querying
where sex='male'
and where sex=1 are equivalent