Common Redis commands

1, Redis global command operation

1. View all keys

keys *
-- Fuzzy search queries can also be used, but generally they are not pushed
keys s*

2. View the total number of keys

dbsize

3. Check if the key exists

exists key

4. Delete key to return the number of deleted entries

del key

5. Key expiration

Return the remaining expiration time: - 1 means no expiration is set, - 2 means expired, and a positive number means the remaining expiration time (seconds)

expire key seconds
-- Expire after setting timestamp
expireat key time stamp
-- See how long it expires
ttl key

6. View the data structure type of the key

type key

7. Key rename

If the newkey exists, it will be forcibly overwritten

rename oldkey newkey

2, Five common data structure operations of Redis

String, Hash, List, Set, ZSET

String (String)

1. Set value

set key value
-- key It must not exist before it can be set successfully for adding
setnx key value
-- key Must exist for setup to succeed for update
set key value xx
--Batch settings
mset key1 value1 key2 value2
 Example:
set age 23 ex 10
setnx name test
set age 25 xx

The set command has several options:

ex seconds: sets the second expiration time for the key.
px milliseconds: sets the millisecond expiration time for the key.
nx: the key must not exist before it can be successfully set for addition.
xx: Contrary to nx, the key must exist before it can be successfully set for update.

set key value ex seconds

2. Get value

get key
--Batch acquisition
mget key1 key2
 Example:
Batch setting: mset country china city beijing
 Batch acquisition: mget country city address

3. lncr digital operation

The lncr command is used to automatically increment the value. The returned results are divided into three cases:

Value is not an integer, error returned
The value is an integer and returns the result after self increment
If the key does not exist, it will increase automatically according to the value of 0, and the return result is 1

-- Self increasing
incr key
-- Self subtraction
decr key
-- Self incrementing specified number
incrby number key
-- Self subtracting specified number
decrby number key
-- Self increasing floating point number
incrbyfloat number key
 Example:
incr age       //Must be an integer self incrementing 1, non integer returns an error, and no age key returns 1 from 0
decr age      //Integer age minus 1
incrby age 2 //Integer age+2
decrby age 2//Integer age -2
incrbyfloat score 1.1 //Floating point score+1.1

4. Append append instruction

append key Appended string
 Example:
set name hello
append name world //Add to helloworld

5. strlen string length, returns the string length

strlen key
 Example:
 set hello ""World"
 strlen hello

6. getset sets and returns the original value

getset sets the same value as set, but the difference is that it also returns the original value of the key

getset key value

7. setrange sets the character at the specified position, and the subscript is calculated from 0

setrange key Value of subscript setting

8. getrange intercept string

getrange intercepts a part of the string to form a substring. It needs to indicate the offset of the start and end. The intercepted range is a closed interval

getrange key Start subscript end subscript
 Example:
 set name helloworld ; getrange name 2 4//Return llo

Hash

id	name	age
1	xiaoming	18

-- use String Set value(Preventing key name conflicts in command space: business name:Object name:id:attribute)
set user:1:name xiaoming
set user:1:age 18
-- use Hash Set value
hmset user:1 name xiaoming age 18

hash is a mapping table of field and value of string type. hash is especially suitable for storing objects

 command  hset key field value
   Set value: hset user:1 name xiaoming
   Value: hget user:1 name
   Delete value: hdel user:1 age
   Number of calculations: hset user:1 name xiaoming; hset user:1 age 23; 
              hlen user:1
   Batch setting: hmset user:2 name xiaoming age 23 sex boy
   Batch value: hmget user:2 name age sex
   judge field Is there: hexists user:2 name
   Get all field: hkeys user:2
   obtain user:2 All value: hvals user:2
   obtain user:2 All field And value: hgetall user:2
   Add 1: hincrby user:2 age 1
   hincrbyfloat user:2 age 2

List

The list type is used to store multiple ordered strings. The five elements a, b, c, d and e form an ordered list from left to right. Each string in the list is called element. A list can store up to 2-1 elements. In Redis, you can insert (push) and pop (pop) at both ends of the list, obtain the element list of the specified range, obtain the elements of the specified index subscript, etc.

1. lrange gets the list of elements within the specified range

Index subscript features: 0 to N-1 from left to right

lrange 0 -1  Command can get all the elements of the list from left to right
rpush Insert from right to left
lpush Insert from left to right
linsert Insert a new element before or after an element
lpop Pop up from the left side of the list
rpop Pop up from the right side of the list

2. lrem deletes the specified element

The lrem command will find an element equal to value from the list and delete it. There are three cases according to the count:

Count > 0, delete up to count elements from left to right.
Count < 0, delete up to count absolute value elements from right to left.
count=0, delete all.

lrem enjoylist 4 x

3. ltirm prunes the list by index range

For example, you want to keep the 0 to 1 elements in the list

ltrim enjoylist 0 1

4. lset modifies the element of the specified index subscript

lset enjoylist 1 web

5. lindex gets the element of the index subscript specified in the list

lindex enjoylist 1

6. llen get list length

llen enjoylist

Set

The set type is also used to store multiple string elements, but unlike the list type,
Duplicate elements are not allowed in the collection, and the elements in the collection are unordered. Elements cannot be obtained through index subscripts.

1. sadd add element

Multiple elements can be added, and the returned result is the number of elements added successfully

sadd key member

2. srem delete element

Multiple elements are allowed to be deleted, and the returned result is the number of successfully deleted elements

srem key member

3. scard calculates the number of elements

scard key

4. sismember determines whether an element is in the collection

If the given element element returns 1 within the collection, otherwise it returns 0

sismember key member

5. srandmember randomly returns the specified number of elements from the collection

If the specified number is not written, the default value is 1

srandmember key count

6. spop randomly ejects elements from the collection

You can specify the number. If you do not write, the default is 1. After the spop command is executed, the element will be deleted from the collection, while the srandmember command will not delete the element

spop key count

7. smembers get all elements

The returned results are unordered

smembers key

8. Finding the intersection of multiple sets by sinter

sinter key1 key2

9. sunion finding the union of multiple sets

sunion key1 key2

10. sdiff finding the difference set of multiple sets

sdiff key1 key2

11. Save the results of intersection, union and difference sets

Operations between sets are time-consuming when there are many elements, so redis provides the following three commands (original command + store) to save the results of intersection, union and difference between sets in the destination key

sinterstore destination key [key ...] 
suionstore destination key [key ...] 
sdiffstore destination key [key ...]

Ordered set (ZSET)

Ordered set retains the feature that the set cannot have duplicate members, but the difference is that the elements in the ordered set can be sorted. It uses index subscripts as the sorting basis compared with the list. The difference is that the ordered set sets a score for each element as the sorting basis.

The elements of an ordered set cannot be repeated, but the score can be repeated, just as the student number of a classmate cannot be repeated, but the score can be repeated.

The ordered set provides functions such as sub obtaining specified scores and element range query, calculating member ranking, etc.

1. zadd adds members, and the returned result represents the number of members successfully added

Add user test01 and his score 98 to the ordered set u:kaoshi:

zadd u:kaoshi 98 test01

The zadd command also has four options nx, xx, ch, incr

nx: member must not exist before it can be set successfully for adding
xx: member must exist before it can be successfully set for update
ch: returns the number of ordered set elements and scores changed after this operation
incr: increase the score, which is equivalent to zincrby

2. zcard calculates the number of members

zcard key

3. zscore calculates the score of a member

nil if the member does not exist

zscore key member

4. zrank calculates the ranking of members

zrank is the score from low to high, and zrevrank is the score from high to low

zrank key member
zrevrank key member

5. zrem delete member

Multiple members can be deleted at one time, and the returned result is the number of successfully deleted members

zrem key member

6. zincrby increases members' scores

zincrby key score member

7. zrange and zrevrange return members of the specified ranking range

Ordered sets are ranked according to scores. zrange returns from low to high. On the contrary, if the WithCores option is added, the scores of members will be returned at the same time

zrange key min max 
zrange key min max withscores
zrevrange key min max
zrevrange key min max withscores

8. zrangebyscore returns the members of the specified score range

zrangebyscore returns from low to high according to the score, and zrevangebyscore returns vice versa.

zrangebyscore key min max [withscores] [limit offset count] zrevrangebyscore key max min [withscores][limit offset count]

9. zcount returns the number of members in the specified score range

zcount key min max

10. zremrangebyrank deletes the elements in the specified ranking in ascending order

zremrangebyrank key start end

11. zremrangebyscore deletes members of the specified score range

zremrangebyscore key min max

12. Zintermore intersection

zinterstore destination numkeys key [key ...] [weights weight [weight ...]] [aggregate sum / min / max]

destination: save the intersection calculation results to this key.

numkeys: the number of keys for intersection calculation.

key [key...]: the key for intersection calculation.

weights weight [weight...]: the weight of each key, and the weight of each key in the intersection calculation

member will multiply its score by this weight, and the weight of each key is 1 by default.

aggregate sum/ min |max: after calculating the intersection of members, the score can be calculated according to sum (and) and min (maximum)

Small value) and max (maximum value) are summarized. The default value is sum

13. zunionstore Union

zunionstore destination numkeys key [key ...] [weights weight [weight ...]] [ aggregate sunmI minl max]

intersection

zinterstore destination numkeys key [key ...] [weights weight [weight ...]] [aggregate sum / min / max]