incr, incrBy
Description
Increment the number stored at key by one. If the second argument is filled, it will be used as the integer value of the increment.
对指定的KEY的值自增1。如何填写了第二个参数，将把第二个参数自增给KEY的值。
Parameters
key
value: value that will be added to key (only for incrBy)
Return value
INT the new value
返回新的INT数值
Examples
$redis->incr('key1'); /* key1 didn't exists, set to 0 before the increment */
/* and now has the value 1 */
$redis->incr('key1'); /* 2 */
$redis->incr('key1'); /* 3 */
$redis->incr('key1'); /* 4 */
$redis->incrBy('key1', 10); /* 14 */