Python – CRUD Operation
As we read earlier about Python list. Now we will study about CRUD Operation, These are neither a method of Python nor any function. It means that these are not a part of Python programming. But if we do this CRUD operation in Python, then we can easily make some python programs. These operations have a lot of advantages for Python programming.
What is CRUD Operation in Python ?
CRUD Operation are those basic and important operation which one should know how to apply after studying “List” data type.
C – CREATE
First, let’s study our first operation of CRUD which is “C” for create which means either to add elements or to insert them.
Here are some functions of CREATE :-
- append
- insert
- extend
As you have studied how to create a list, let us create a list first.
list_1 = [1, 2, 3, 4]
⇒ append :
Append is a function of list that add given element at the end of the list.
General syntax for append :
list.append(self, element)Suppose we want to add an element ” 5 ” at the end of a list, what we can do is to use append( ) function.
Example :
list_1 = [1,2,3,4]
list_1.append(5)
print(list_1)
Output :
[1, 2, 3, 4, 5]
You can also append a list.
Example :
list_1 = [1,2,3,4]
list_2 = [5,6,7,8]
list_1.append(list_2)
print(list_1)
Output :
[1, 2, 3, 4, [5, 6, 7, 8]]As we can see the list_2 just got appended to list_1.
⇒ insert :
Insert is a function of list that add element at given index position.
General syntax for insert :
list.insert(self, index, element)
Example :
list_1 = [1,2,3,4]
list_1.insert(1,5)
print(list_1)
Output :
[1, 5, 2, 3, 4]
You can apply insert( ) and append( ) both at a time.
Example :
list_1 = [1,2,3,4]
list_1.insert(1,[11,22,33,44])
list_1.append([55,66,77,88])
print(list_1)
Output :
[1, [11, 22, 33, 44], 2, 3, 4, [55, 66, 77, 88]]
You can add element at given index position into a list of list.
Example :
list_1 = [1,2,3,4]
list_1.insert(1,[11,22,33,44])
list_1.append([55,66,77,88])
list_1[1].insert(1,7)
print(list_1)
Output :
[1, [11, 7, 22, 33, 44], 2, 3, 4, [55, 66, 77, 88]]
⇒ extend :
The extend( ) is a function of list that adds the specified list elements ( or any iterable ) to the end of the current list.
General syntax for extend( ) :
list.extend(self, iterable)
Example :
list_1 = [1,2,3,4]
list_2 = [11,22,33,44]
list_1.extend(list_2)
print(list_1)
Output :
[1, 2, 3, 4, 11, 22, 33, 44]
Another way to add the specified list elements to the end of the current list.
Example :
list_1 = [1,2,3,4]
list_2 = [11,22,33,44]
list_3 = list_1 + list_2
print(list_3)
Output :
[1, 2, 3, 4, 11, 22, 33, 44]
You can also add string ( one by one ) to the end of the current list.
Example :
list_1 = [11,22,33,44]
list_1.extend("abcd")
print(list_1)
Output :
[11, 22, 33, 44, 'a', 'b', 'c', 'd']
You can also add string to the end of the current list with the help of extend( ) function.
Example :
list_1 = [11,22,33,44]
list_1.extend(["Black"])
print(list_1)
Output :
[11, 22, 33, 44, 'Black']
R – READ
Let’s study our second operation of CRUD which is ” R ” for read which means either to read data or to search data from the list.
Here are some functions of READ :-
- index
- _ _contains_ _
- count
Let us create a list first.
list_1 = [1, 2, 3, 4]
⇒ index :
Index functions search element into list, if found returns index positions of element, otherwise returns error.
General syntax for index( ) :
list.index(self, element, start, end)
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.index(2)
print(i)
Output :
2
There are three 1’s in list1. You can also search the first “1” from list1 using index( ) functions, if found returns index position of element.
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.index(1)
print(i)
Output :
0
You can also search the second “1” from list_1 using index( ) functions, if found returns index position of element.
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.index(1,1)
print(i)
Output :
3
You can also search the third “1” from list+1 using index( ) functions, if found returns index position of element.
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.index(1,4)
print(i)
Output :
6
⇒ _ _contains_ _ :
_ _contains_ _( ) function which will return boolean value. True means the element exists and False means there is no such element in the list.
General syntax for _ _contains_ _( ) :
list._ _contains_ _(self, element)
Elements are exists in list 1.
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.__contains__(7)
print(i)
Output :
True
Elements are not exist in list 1.
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.__contains__(10)
print(i)
Output :
False
⇒ count( ) :
count( ) function which will return you the count of the element that you pass in it. count( ) function always return integer data type.
General syntax for count ( ) :
list.count(self, element)
Example :
list_1 = [1,3,2,1,5,7,1,8]
i=list_1.count(1)
print(i)
Output :
3
U – UPDATE
Let’s study our third operation of CRUD which is “U” for update operation is used to modify the contents of a list or to make changes in a list.
Example :
list_1 = [11,22,33,44,55]
list_1[2]=300
print(list_1)
Output :
[11, 22, 300, 44, 55]
D – DELETE
Let’s study our last operation of CRUD which is “D” for delete operation is used to remove an element from the list.
Here are some functions of DELETE :-
- remove
- pop
- clear
let us create a list first.
list_1 = [1,2,3,4,5]
⇒Remove :
Remove method search given element if found then remove it, otherwise returns an Error.
General syntax for remove( ) :
list.remove(self, element)
Example :
list_1 = [1,2,3,4,5]
list_1.remove(3)
print(list_1)
Output :
[1, 2, 4, 5]
⇒ pop( ) :
Remove element of given index position and return removed elements, if index is not found returns Error.
General syntax for pop( ) :
list.pop(self, index)
Example :
list_1 = [1,2,3,4,5]
list_1.pop()
print(list_1)
Output :
[1, 2, 3, 4]
Another example :
list_1 = [1,2,3,4,5]
list_1.pop(3)
print(list_1)
Output :
[1, 2, 3, 5]
⇒ clear( ) :
It removes all the elements from the given list.
Example :
list_1 = [1,2,3,4,5]
list_1.clear()
print(list_1)
Output :
[ ]
More functions :
1. Reverse( ) : Reverse the order of the list.
General syntax for reverse( ) :
list.reverse(self)
Example :
list_1 = [1,2,3,4,5]
list_1.reverse()
print(list_1)
Output :
[5, 4, 3, 2, 1]
2. del : The del keyword removes the specified index.
Example :
list_1 = [1,2,3,4,5]
del list_1[2]
print(list_1)
Output :
[1, 2, 4, 5]
The del keyword removes the list completely.
Example :
list_1 = [1,2,3,4,5]
del list_1
Output :
The above output will be blanked.
3. sort( ) : Sorts the list.
Example :
list_1 = [1,4,2,8,6,3]
list_1.sort()
print(list_1)
Output :
[1, 2, 3, 4, 6, 8]
Important Note : If you want to create a project like the ” CUSTOMER MANAGEMENT SYSTEM ” then you must remember the ” CRUD Operation “, this will make you easier to create the project.
I want to build a Customer Management System, so I will need CRUD Operation i.e. C ( create ) means add customer, R ( read ) means search customer, U ( update ) means modify customer and D ( delete ) means delete customer.
If you make such a project, then you just have to remember the CRUD Operation.
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