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Cluster cluster addslots(集群 槽位) cluster count failure reports(集群計(jì)數(shù)失敗報(bào)告) cluster countkeysinslot cluster delslots cluster failover cluster forget cluster getkeysinslot cluster info cluster keyslot(集群鍵槽) cluster meet cluster nodes(集群節(jié)點(diǎn)) cluster replicate(集群復(fù)制) cluster reset(集群重置) cluster saveconfig cluster set config epoch cluster setslot cluster slaves cluster slots readonly readwrite Connection auth echo ping quit select swapdb Geo geoadd geodist geohash geopos georadius georadiusbymember Hashes hdel hexists hget hgetall hincrby hincrbyfloat hkeys hlen hmget hmset hscan hset hsetnx hstrlen hvals HyperLogLog pfadd pfcount pfmerge Keys del dump exists expire expireat keys migrate move object persist pexpire pexpireat pttl randomkey rename renamenx restore scan sort touch ttl type unlink wait Lists blpop brpop brpoplpush lindex linsert llen lpop lpush lpushx lrange lrem lset ltrim rpop rpoplpush rpush rpushx Pub/Sub psubscribe publish pubsub punsubscribe subscribe unsubscribe Scripting eval evalsha script debug script exists script flush script kill script load Server bgrewriteaof bgsave client getname client kill client list client pause client reply client setname command command count command getkeys command info config get config resetstat config rewrite config set dbsize debug object debug segfault flushall flushdb info lastsave monitor role save shutdown slaveof slowlog time Sets sadd scard sdiff sdiffstore sinter sinterstore sismember smembers smove spop srandmember srem sscan sunion sunionstore Sorted Sets zadd zcard zcount zincrby zinterstore zlexcount zrange zrangebylex zrangebyscore zrank zrem zremrangebylex zremrangebyrank zremrangebyscore zrevrange zrevrangebylex zrevrangebyscore zrevrank zscan zscore zunionstore Strings append bitcount bitfield bitop bitpos decr decrby get getbit getrange getset incr incrby incrbyfloat mget mset msetnx psetex set setbit setex setnx setrange strlen Transactions discard exec multi unwatch watch
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EXISTS key [key ...]

自1.0.0起可用。

時(shí)間復(fù)雜度: O(1)

返回如果key存在。

自 Redis 3.0.3 以來,可以指定多個(gè)密鑰而不是單個(gè)密鑰。在這種情況下,它會返回現(xiàn)有密鑰的總數(shù)。請注意,為單個(gè)鍵返回1或0只是可變參數(shù)使用的特例,因此該命令完全向后兼容。

用戶應(yīng)該知道,如果多次在參數(shù)中提及相同的現(xiàn)有密鑰,它將被多次計(jì)數(shù)。所以如果somekey存在,EXISTS somekey somekey將返回2。

返回值

整數(shù)回復(fù),具體為:

  • 1 如果密鑰存在。

  • 0 如果密鑰不存在。

自 Redis 3.0.3 以來,該命令接受可變數(shù)量的鍵并將返回值進(jìn)行了概括:

  • 存在于指定為參數(shù)的鍵中的鍵的數(shù)量。鍵提及多次,現(xiàn)有計(jì)數(shù)多次。

例子

redis>  SET key1 "Hello" "OK" 

redis>  EXISTS key1 (integer) 1 

redis>  EXISTS nosuchkey (integer) 0 

redis>  SET key2 "World" "OK" 

redis>  EXISTS key1 key2 nosuchkey (integer) 2

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