hmset(hash multiple set) 一次性设置和更新多个字段，执行成功返回ok

127.0.0.1:6379> keys *
(empty list or set)
#如果没有user:1这个key,会自动创建，并写入字段数据
127.0.0.1:6379> hmset user:1 name youyi age 12
OK
127.0.0.1:6379> hgetall user:1
1) "name"
2) "youyi"
3) "age"
4) "12"
---------------------------------------------------------------
127.0.0.1:6379> keys *
1) "user:1"
127.0.0.1:6379> hgetall user:1
1) "name"
2) "youyi"
3) "age"
4) "12"
#与hset不同的是更新key中已有字段的值也会返回ok
127.0.0.1:6379> hmset user:1 name adc age 17
OK
127.0.0.1:6379> hgetall user:1
1) "name"
2) "adc"
3) "age"
4) "17"