Redis hash type

The key value of hash type is also a dictionary structure, which stores the mapping of field and field value, but the field value can only be a character string, and other data types are not supported. In other words, hash type cannot nest other data types. A hash-type key can contain up to 2^32-1 fields. Other than hash types, Redis also does not support nesting of data types. For example, each element of a collection type can only be a string, not another collection or hash table.

Hash types are appropriate for storing objects: they use object categories and object IDs to form key names, fields to represent attributes of objects, and field values to store attribute values. For example, to store a car object with ID 2, three fields named color, name, and price could be used to store the color, name, and price of the car.

Assignment and value:HSET key field valueHGET key fieldHMSET key field value [field value...] HMGET key field [field ...] HGETALL key Determine whether the field exists:HEXISTS key field When the field does not exist Assign:HSETNX key field value Increase number:HINCRBY key field increase Delete field:HDEL key field [field...] Get field name only:HKEYS key Get field value only:HVALS key Number of fields obtained:HLEN key