hget(hash get) 获取一个key的单个字段数据

127.0.0.1:6379> keys *
1) "user:1"
127.0.0.1:6379> hkeys user:1
1) "name"
2) "age"
127.0.0.1:6379> hget user:1 name
"youyi"
127.0.0.1:6379> hget user:1 age
"20"
127.0.0.1:6379> hget user:1 df
(nil)
127.0.0.1:6379> hexists user:1 df
(integer) 0