hincrby(hash increment by) 对key中的字段的数值进行加减操作

#对字段进行加和减，加是正数，减是负数，返回值是当前字段的数值
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 age
"20"
127.0.0.1:6379> hincrby user:1 age 10
(integer) 30
127.0.0.1:6379> hincrby user:1 age -10
(integer) 20
127.0.0.1:6379> hget user:1 age
"20"