Iii. List-related operations of redis

=======================================Three types: list type =================================
Introduction: List type and operations
List is the result of a chain table, as long as the function is push, Pop, get all values in a range, etc,
The operation key is interpreted as the name of the linked list. The list type of redis is actually a two-way linked list with each sub-element being a string type.
We can add and delete elements from the head or tail of the linked list through the push and pop operations, so that the list can be both a stack and a queue.

1: lpush:
Add a string element to the header of the list corresponding to the key (advanced, similar to stack)
For example, lpush list1 "hello"
Lpush list1 "world"
Value: lrange list1 0-1 --> retrieve from the beginning to the end, and retrieve all the items in list1.
2: rpush
Add a string element at the end of the list corresponding to the key (first, similar to the queue)
Example: rpush list2 "Le"
Rpush list2 "yangjun"
Take: lrange list2 0-1 --> le yangjun Value
3: linsert:
Add a string before or after a specific position of the list corresponding to the key
For example, lpush list3 "one"
Lpush list3 "two"
Linsert list3 before one three ---> press a three between one and two
Lrange list2 0-1
4: lset:
Set the value of the specified subscript element in the list.
For example, lpush list5 one
Lpush list5 two
Lset list5 1 "four" ----> change the value of 1 in the following table to four.
5: lrem: Delete the value of the same element
Delete n elements with the same value from the list corresponding to the key (n <0 is deleted from the end, n = 0 all are deleted)
For example, lpush list5 one
Lpush list5 one
Lrem lise5 1 "one" ---> 1: delete several items. delete one element with the same one from list5.
Lrem lise5 0 "one" ---> delete all
6: ltrim:
Retain data within the value range of a specified key
For example, lpush list6 one
Lpush list6 two
Lpush list6 three
Ltrim list6 1-1 --> retain the value of subscript 1-1, delete all others
Ltrim list6 1 2 ---> retain the subscripts 1 and 2, and delete other
7: lpop:
Deletes an element from the list header and returns the deletion element.
Example: rpush list8 one
Rpush list8 two
Lpop list8 --> pop up one, that is, delete it, leaving only two
8: rpop:
Deletes an element from the end of the list and returns the deletion element.
Example: rpush list8 one
Rpush list8 two
Rpop list8 ---> two pops up at the end, with only one
9: rpoplpush:
Removes elements from the end of the first list and adds them to the header of the second list.
Example: list9: Three, hello list10: Hello, foo
Rpoplpush list9 list10 ---> hello, from the end of list9, and hello, pushed from the header to list10.
List10 = Hello, Hello, foo
10: lindex:
Returns the index position element in the list named key.
Example: list11: Three, two, one
Lindex list11 0 ---> Find the element 0 in the following table-> three
11: llen:
Returns the length of the list corresponding to the key.
For example, llen list11 --> Returns a few elements. For example, if one there is returned, 1 is returned.
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