Redis Learning Lesson Two: Redis hash types and operations

Redis Hash is a string-type field and value mapping table. Its addition, delete operations are O (1) (average). Hash is particularly useful for storing objects. there is a single string type compared to each field of an object. Storing an object in a hash type takes up less memory and makes it easier to access the entire object.

Hset: Sets the hash field to the specified value, and if key does not exist, it is created first.

Hget: Gets the specified hash field.

127.0.0.1:6379>hset user:001 name Tom

(integer) 1

127.0.0.1:6379>hset user:001 Age 28

(integer) 1

127.0.0.1:6379>hget user:001 Name

"Tom"

HSETNX: Sets the hash field to the specified value, and if key does not exist, it is created first. Returns 0 if it exists.

127.0.0.1:6379>hset user:001 name Jack

(integer) 0

Hmset: Set multiple fields of hash at the same time.

Hmget: Gets all the specified hash field.

127.0.0.1:6379> hmset user:002 ID 1 name Mark sex male Age 29

Ok

127.0.0.1:6379> Hget user:002

(Error) ERR wrong number of arguments for ' hget ' command

127.0.0.1:6379> hmget user:002 ID name male age

1) "1"

2) "Mark"

3) (nil)

4) "29"

Hincrby: Specifies the hash field plus the given value.

127.0.0.1:6379> Hincrby user:002 age 6

(integer) 35

127.0.0.1:6379> Hincrby user:002 age-2

(integer) 33

Hexists: test Specifies whether the field exists in the hash.

127.0.0.1:6379> hexists user:002 Sex

(integer) 1

127.0.0.1:6379> hexists user:001 Sex

(integer) 0

Hlen: Returns the number of field for the specified hash.

127.0.0.1:6379> Hlen user:001

(integer) 2

127.0.0.1:6379> Hlen user:002

(integer) 4

Hdel: Deletes the field of the specified hash.

127.0.0.1:6379> Hdel user:002 Sex

(integer) 1

127.0.0.1:6379> hget user:002 Sex

(nil)

Hkeys: Returns all field of the hash.

127.0.0.1:6379> Hkeys user:002

1) "id"

2) "Name"

3) "Age"

127.0.0.1:6379> Hkeys user:001

1) "Name"

2) "Age"

Hvals: Returns all value of the hash.

127.0.0.1:6379> hvals user:002

1) "1"

2) "Mark"

3) "33"

Hgetall: Gets all the field and value in a hash.

127.0.0.1:6379> Hgetall user:002

1) "id"

2) "1"

3) "Name"

4) "Mark"

5) "Age"

6) "33"

Redis Learning Lesson Two: Redis hash types and operations