Introduction to common commands and syntax of Redis

Redis is a high-performance NoSQL (non-relational database) technology that uses memory storage, so its read and write speeds are very fast. The common commands and syntax of Redis can help developers better understand and use this technology. The common commands and syntax of Redis will be introduced below.

1. Data type

Redis supports the following five data types:

• String (string): can store strings, integers and Floating point number.
• List (list): can store an ordered list of strings.
• Set (set): can store unordered, unique string collections and supports set operations.
• Hash: An unordered hash table that can store key-value pairs.
• Zset (ordered set): can store an ordered, unique set of strings and supports sorting.

2. String commands

Redis provides common string commands, such as set (set value), get (get value), mset (set multiple value), mget (get multiple values), etc. For example:

set key value   // 设置键key的值为value
get key         // 获取键key的值
mset key1 value1 key2 value2   // 分别设置键key1和key2的值为value1和value2
mget key1 key2  // 获取键key1和key2的值

3. List commands

Redis’ list commands include lpush (adding values ​​from the left), rpush (adding values ​​from the right), lpop (adding values ​​from the left) remove the value), rpop (remove the value from the right), etc. For example:

lpush list value1    // 将值value1添加到列表list的左边
rpush list value2    // 将值value2添加到列表list的右边
lpop list            // 删除并返回列表list的左边第一个值
rpop list            // 删除并返回列表list的右边第一个值

4. Collection commands

Redis’ collection commands include sadd (add value), scard (get the number of elements in the collection), sismember (judge value) whether it is in the set) etc. For example:

sadd set value1     // 将值value1添加到集合set中
scard set           // 获取集合set的元素个数
sismember set value1    // 判断值value1是否在集合set中

5. Hash command

Redis’ hash commands include hset (set value), hget (get value), hdel (delete value), hexists (to determine whether the value exists), etc. For example:

hset hash key value    // 在哈希表hash中设置键key的值为value
hget hash key          // 获取哈希表hash中键key的值
hdel hash key          // 删除哈希表hash中键key的值
hexists hash key       // 判断哈希表hash中是否存在键key

6. Ordered set commands

Redis’ ordered set commands include zadd (add value), zrange (get elements ranked within the interval) , zrevrange (get the elements ranked in the interval in reverse order), etc. For example:

zadd zset 1 value1    // 将值value1添加到有序集合zset中，并指定排名为1
zrange zset 0 2       // 获取有序集合zset中排名在0到2的元素
zrevrange zset 0 2    // 获取有序集合zset中倒序排名在0到2的元素

In addition to the above commands, Redis also provides many other commands, such as incr (self-increment), expire (set expiration time), etc., which can be learned and understood through the official documentation. Generally speaking, Redis's common commands and syntax are very concise and easy to understand, and it is also very convenient to use, so it is a NoSQL technology favored by many developers.

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