What are the common operation commands of Redis basic data type List?

##Redis data type List operation

In redis , you can cleverly use lists into stacks, queues, blocking queues, etc.

1. Push insert elements

1. lpush, insert at the head

Insert one value or multiple values ​​into the head of the list.

lpush list onelpush list twolpush list three

Use

lpush, the l here can be regarded as left, that is, inserted on the left, so the current list is like this[three , two, one].

2. rpush, insert

Next, use

rpush to insert elements on the right, that is, at the end of the list.

rpush list right1 right2

At this time, the list is like this

[three, two, one, right1, right2]. Use lrange list 0 -1 to get:

2. Range Get elements through intervals

can be imagined as in python

range(), get the element by passing in the start and end subscripts.

lrange list 1 4

3. Pop removal element

Since the above can be added to the left and right, then the removal can naturally be divided into left and right.

Removal operation returns the removed element.

1. lpop removes the left side

lpop list

2. rpop removes the right side

rpop list

4. lindex gets the element through the subscript

lindex list 1

5. llen gets the list length

Returns the length of the list.

llen list

6. lrem removes specified elements

You can specify the element to be removed, and specify the number.

lrem list 2 yi222

There are 3 yi222s in the list now, and I want to remove 2 of them.

7. ltrim trimming

Through

ltrim, only the specified part is retained, and other parts are removed, and the intercepted list changes. .

ltrim list 1 4

Here the subscripts from 1 to 4 are retained, and the others are removed.

8. Combination command rpoplpush remove and add

This is a combination command, remove the last element of the list and add it to another list .

rpoplpush list list2

Here

list is the original list, list2 is the target list, and if the target list does not exist, it will be created.

9. exists Determine whether the key exists

exists list

Returns 1 if it exists, and returns 0 if it does not exist.

10. lset, set the value of the specified subscript

lset list 1 test

When the index parameter is out of range, or LSET is performed on an empty list, an error is returned.

11. linsert, insert the value before/after the specified position

before

linsert list before test before_test

This is the element

testBefore, insert element before_test.

After

linsert list after test after_test

This is after element

test, insert element after_test.

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