Introduction to basic commands of 5 data types in redis

redis is a database of key-value pairs. There are 5 main data types:

String type (string), hash type (hash), list type ( list), set type (set), ordered set type (zset)

Recommended: redis tutorial

Several basic commands:

##keys *Get all keys of the current databaseexists key [key ...]Determine whether the key exists and return the number. If the key has the same key, it will also be a superposition numberdel key [key ...]Delete key, return the number of deleted itemstype keyGet the reduced value Data type (string, hash, list, set, zset)flushallClear all databasesconfig [get , set]redis configuration

-inf negative infinity

inf positive infinity

1: String type (string)

The string type is the most basic type of Redis, it can store any string in the form. The other four types are all different forms of the string type.

Function	Description

Function	Syntax
The most basic commands: GET, SET	GET key, SET key value If there are spaces, double quotes are needed to distinguish the value.
Integer increment: INCR	INCR key The default value is 0, So first execute the command to get 1, which is not an integer and prompts an error
Increase the specified integer: INCRBY	INCRBY key increment
Decrease the integer: DECR	DECR key The default value is 0, so first execute the command to get -1, which is not an integer and prompt an error
Decrease the specified integer: DECRBY	DECRBY key increment
Increase the specified floating point number: INCRBYFLOAT	INCRBYFLOAT key increment is similar to the INCR command, except that it can increment a double-precision floating point number
Append value to the end: APPEND	APPEND key value The redis client does not output the appended string, but outputs the total length of the string
Get the string length: STRLEN	STRLEN key If the key does not exist, return 0. Note that if there is Chinese, the length of a Chinese character is 3, and redis uses UTF-8 to encode Chinese
Get multiple key values: MGET	MGET key [key ...] For example: MGET key1 key2
Settings Multiple key values: MSET	MSET key value [key value ...] For example: MSET key1 1 key2 "hello redis"
Binary specified position value: GETBIT	GETBIT key offset For example: GETBIT key1 2, key1 is hello and returns 1. The returned value is only 0 or 1. When the key does not exist or exceeds the actual length, it is 0
Set the binary position value: SETBIT	SETBIT key offset value, return the old value of the position
The binary number is 1: BITCOUNT	BITCOUNT key [start end], start and end are the start and end bytes
Bit operation: BITOP	BITOP operation destkey key [ key ...], operation supports AND, OR, XOR, NOT
Offset: BITPOS	BITPOS key bit [start] [end]

Two: Hash type (hash)

Function	Syntax
Set a single: HSET	HSET key field value, returns 1 if it does not exist, returns 0 if it exists, there is no distinction between update and insertion
Set multiple: HMSET	HMSET key field value [field value ...]
Read a single: HGET	HGET key field, if it does not exist, return nil
Read multiple: HMGET	HMGET key field [field ...]
Read all: HGETALL	HGETALL key, return a list of fields and field values
Judge whether the field exists: HEXISTS	HEXISTS key field, return 1 if it exists, if not Existence returns 0
Assignment when the field does not exist: HSETNX	HSETNX key field value, different from the hset command, hsetnx sets the value when the key does not exist
Increase number: HINCRBY	HINCRBY key field increment, return the increased number, if it is not an integer, an error will be prompted
Delete field: HDEL	HDEL key field [field ...], returns the number of deleted fields
Get only the field name: HKEYS	HKEYS key , return all field names of the key
Get only field values: HVALS	HVALS key , return all field values ​​of the key
Number of fields: HLEN	HLEN key, return the total number of fields

Three: List type (list)

Internally implemented using a doubly linked list, so the elements closer to both ends are obtained faster, but access through indexes will be slower

Function	Syntax
Add the left element: LPUSH	LPUSH key value [value .. .] , returns the total number of added list elements
Add the right element: RPUSH	RPUSH key value [value ...] , returns the added The total number of list elements
Remove the first element on the left: LPOP	LPOP key, return the value of the removed element
Remove the first element on the right: RPOP	RPOP key, return the value of the removed element
Number of elements in the list: LLEN	LLEN key, returns 0 when it does not exist. Redis directly reads the ready-made value, not the statistical number
Get the list fragment: LRANGE	LRANGE key start stop, if start is later than stop, an empty list is returned, 0 -1 returns the entire list when it is a positive number: start starts the index value, stop ends the index value (the index starts from 0) when it is a negative number: for example, lrange num -2 -1, -2 means the second from the right, -1 means the first from the right,
Delete the specified value: LREM	LREM key count value, returns the deleted number count>0, deletes the first count elements with value from the left count<0, deletes the previous ones from the right |count| elements whose value is value count=0, delete all elements whose value is value
Index element value: LINDEX	LINDEX key index, returns the element value of the index, -1 means setting the element value from the rightmost first position
: LSET	LSET key index value
Keep list fragment: LTRIM	LTRIM key start stop, start, top refer to lrange command
Transfer one list to another List: RPOLPPUSH	RPOPLPUSH source desctination, transfer from the source list to the desctination list. This command is divided into two steps. First, remove the source list RPOP right, and then remove the desctination list LPUSH

Four: Set type (set)

Set type values ​​are unique. Common operations are to add, delete, and determine whether a value exists in the set. The internal set is implemented using a hash table with empty values. of.

Function	Syntax
Add element: SADD	SADD key member [member ...], adds one or more elements to a set. Because of the uniqueness of the set, adding the same value will be ignored. Returns the number of successfully added elements.
Delete elements: SREM	SREM key member [member ...] Delete one or more elements in the collection and return the number of successfully deleted elements.
Get all elements: SMEMBERS	SMEMBERS key, return all elements of the collection
Whether the value exists: SISMEMBER	SISMEMBER key member, if it exists, it returns 1, if it does not exist, it returns 0
Difference operation: SDIFF	SDIFF key [key ...], For example: set A and set B, the difference set represents A-B, if there are elements in A that are not in B, the difference set is returned; multiple sets (A-B)-C
intersection operation: SINTER	SINTER key [key ...], returns the intersection set, each set has elements
And operation: SUNION	SUNION key [key...], returns the union set, the elements of all sets
The number of set elements: SCARD	SCARD key, returns the number of set elements
Storage results after set operation	SDIFFSTROE destination key [key ...], difference operation and store in destination new setSINTERSTROE destination key [key .. .], intersect and store it in the new collection of destination SUNIONSTROE destination key [key ...], and perform the operation and store it in the new collection of destination
Randomly obtain elements: SRANDMEMGER	SRANDMEMBER key [count], there are different results depending on the count. When the count is greater than the total number of elements, all elements count>0 are returned. Count
Pop element: SPOP	SPOP key [count], because the collection is unordered, So spop will randomly pop up an element

Five: Ordered set type zset (sorted set: ordered set)

Redis zset, like set, is also a collection of string type elements, and duplicate members are not allowed.

The difference is that each element is associated with a double type score.

Redis uses scores to sort the members of the set from small to large. The members of zset are unique, but the scores can be repeated.

##Add a collection element: ZADDZADD key [NX|XX] [CH] [INCR] score member [score member ...], there is no addition, there is update. Get the element score: ZSCOREZSCORE key member, return the score score of the element memberElements from small to large: ZRANGEElements from large to small: ZREVRANGEZREVRANGE key start [WITHSCORES], the difference from zrange is that zrevrange is sorted from large to smallSpecifies the score range Element: ZRANGEBYSCORESpecify the score range elements: ZREVRANGESCOREIncrease the score ：ZINCRBYZINCRBY key increment member, note that the score is increased and the increased score is returned; if the member does not exist, a member of 0 is added.

Function	Syntax
	ZRANGE key start top [WITHSCORES], refer to LRANGE, plus withscores to return the band elements, that is, elements, scores. When the scores are the same, sort by elements
	ZRANGEBYSCORE key min max [WITHSCORE] [LIMIT offest count] returns the elements between min and max from small to large, ( symbol means not included, for example: 80-100, (80 100, withscore returns the mixed fraction limit offest count, offset offset count to the left, and obtain the first count elements
	ZREVRANGEBYSCORE key max min [WITHSCORE] [LIMIT offest count] is similar to zrangebyscore, except that the command is sorted from large to small.

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