redis ZCARD command

1. card

##UK[kɑ:d] US[kɑ:rd]

n.Card; Credit card; playing cards; postcard

vt. recorded on the card

Third person singular: cards Plural: cards Present participle: carding Past tense: carded Past participle: carded

redis ZCARD command syntax

Function:Returns the cardinality of the ordered set key.

Syntax:ZCARD key

Available versions:>= 1.2.0

Time complexity:O(1)

Return:When key exists and is an ordered set type, return the cardinality of the ordered set. When key does not exist, return 0.

redis ZCARD command example

redis > ZADD salary 2000 tom # 添加一个成员 (integer) 1 redis > ZCARD salary (integer) 1 redis > ZADD salary 5000 jack # 再添加一个成员 (integer) 1 redis > ZCARD salary (integer) 2 redis > EXISTS non_exists_key # 对不存在的 key 进行 ZCARD 操作 (integer) 0 redis > ZCARD non_exists_key (integer) 0