Redis（七）：Hash哈希数据类型详解

Redis hash 是一个 string 类型的 field 和 value 的映射表，hash 特别适合用于存储对象。

Redis 中每个 hash 可以存储 232 - 1 键值对（40多亿）。

实例：

127.0.0.1:6379>  HMSET runoobkey name "redis tutorial" description "redis basic commands for caching" likes 20 visitors 23000
OK
127.0.0.1:6379>  HGETALL runoobkey
1) "name"
2) "redis tutorial"
3) "description"
4) "redis basic commands for caching"
5) "likes"
6) "20"
7) "visitors"
8) "23000"

1、HASH常用命令

1.1、hset、hmget

127.0.0.1:6379> hset myhash field v1	//set一个key-value
(integer) 1
127.0.0.1:6379> hget myhash field	//获取一个字段值
"v1"
127.0.0.1:6379> hset myhash field2 v2 field3 v3	//set多个key-value
(integer) 2
127.0.0.1:6379> hmget myhash field2 field3	//获取多个字段值
1) "v2"
2) "v3"
127.0.0.1:6379> hgetall myhash	//获取hash中全部数据
1) "field"
2) "v1"
3) "field2"
4) "v2"
5) "field3"
6) "v3"

1.2、hdel

127.0.0.1:6379> hgetall myhash
1) "field"
2) "v1"
3) "field2"
4) "v2"
5) "field3"
6) "v3"
127.0.0.1:6379> hdel myhash field	//删除指定的key字段以及对应的value值。
(integer) 1
127.0.0.1:6379> hgetall myhash
1) "field2"
2) "v2"
3) "field3"
4) "v3"
127.0.0.1:6379>

1.3、hlen

127.0.0.1:6379> hlen myhash	//获取hash字段长度
(integer) 2

1.4、HEXISTS

127.0.0.1:6379> HEXISTS myhash foeld2	//判断hash中指定字段是否存在
(integer) 0
127.0.0.1:6379> HEXISTS myhash field2
(integer) 1

1.5、hkeys、hvals

127.0.0.1:6379> hkeys myhash	//获取所有field
1) "field2"
2) "field3"
127.0.0.1:6379> hvals myhash	//获取所有value
1) "v2"
2) "v3"

1.6、hincrby、hsetnx

127.0.0.1:6379> hset myhash field4 1	
(integer) 1
127.0.0.1:6379> HINCRBY myhash field4 1	//指定增量
(integer) 2
127.0.0.1:6379> HINCRBY myhash field4 -2
(integer) 0
127.0.0.1:6379> HSETNX myhash hield5 v5//如果不存在可以设置，存在不可以设置
(integer) 1
127.0.0.1:6379> HSETNX myhash hield5 v6
(integer) 0