ZADDAdd members with scores to a sorted set, with conditional flags.
| 语法 | ZADD key [NX|XX] [GT|LT] [CH] [INCR] score member [score member ...] |
| 分组 | zset |
| 参数个数 | -4 |
| 起始版本 | 1.0.0 |
| 标志 | write |
| 复杂度 | O(M log N) — O(1) hash insert plus O(log N) tree insert per member |
| Redis 兼容性 | full |