IEnumerable, IEnumerator, IQueryable in C# .NET — Transcript

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1. 0:01what is I enumerable in C in the code
2. 0:04here is a list of employee okay and in
3. 0:07employee class we have ID and name
4. 0:10property now here we are adding new
5. 0:13employees in the code list here okay in
6. 0:15the list here okay then we are running a
7. 0:17for each Loop to print the employees ID
8. 0:18and names one by one now the loop is
9. 0:21working for the employee list this Loop
10. 0:23is working because uh this Loop how this
11. 0:26Loop is working because the list is
12. 0:28derived from I in able interface only
13. 0:31and I inter I enumerable interface is
14. 0:34used when we want to iterate among our
15. 0:37collection classes using a forre loop
16. 0:40you might not use it directly this iable
17. 0:44but all our collection classes like list
18. 0:47which are able to use for each Loop are
19. 0:50internally using this iable interface
20. 0:53like if I will right click on this list
21. 0:55collection and go to the definition and
22. 0:58see list is derived from from the I
23. 1:00numerable right that's it so internally
24. 1:04all the collections are using iable
25. 1:06interface so then only we are able to
26. 1:09iterate the loop uh the collections
27. 1:11through the for each Loop what is the
28. 1:14difference between I inable and I
29. 1:16numerator in C let's see the code first
30. 1:20you know list is using I numerable
31. 1:22internally right and here we are
32. 1:24assigning list to I numerable and then
33. 1:27iterating okay and here is the output
34. 1:30now you can do the same thing using I
35. 1:32enumerator also see here we call get
36. 1:35enumerator method and use move next
37. 1:37method to iterate through the results
38. 1:40and it will give exactly the same output
39. 1:43which iable was giving but the
40. 1:45difference is iable code looks simp
41. 1:49looks simple to implement right so
42. 1:51basically iable internally uses I
43. 1:55numerator only to iterate The Collection
44. 1:57via for each Loop but we use I numerable
45. 2:01because I numerable simplifies the use
46. 2:04of I numerator see list is inherited
47. 2:07from I numerable and I numerable uses I
48. 2:11numerator interface and if you right
49. 2:14click on I numerable and go to the
50. 2:16definition then see here you will find
51. 2:18the get enumerator method which is rning
52. 2:21the type of the I numerator that's
53. 2:26it now here is a very important question
54. 2:29what is the difference between I
55. 2:31numerable and I queriable in C why to
56. 2:34use I queriable for SQL queries we
57. 2:38already know what is I enumerable right
58. 2:40now we will more focus on I quable first
59. 2:44remember this point about I quable I
60. 2:47quable inherited from I numerable
61. 2:49interface only so anything you can do
62. 2:52with I numerable you can also do that
63. 2:55with I variable also for example
64. 2:58iterating the collection can be done by
65. 3:00both I numerable and I variable when you
66. 3:04right click and see the definition of I
67. 3:06quable you will find this see I quable
68. 3:09is inherited from I numerable so
69. 3:12whatever I numerable can do I queriable
70. 3:15can also do in addition I queriable can
71. 3:18perform some extra tasks related to SQL
72. 3:21queries that I will shortly explain okay
73. 3:25now see the code here here we have a
74. 3:27list which we are iterating using I
75. 3:30numerable and here is the output now we
76. 3:33can use I quable also to iterate the
77. 3:36same list and we will get the same
78. 3:38result now the point is why we need I
79. 3:42quable when I enumerable is already
80. 3:44there the reason is inable is used with
81. 3:49and it is preferred with in memory
82. 3:51collections like array array list all
83. 3:54these are in memory collections in
84. 3:56memory objects also you can see whereas
85. 3:59I variable is better in getting results
86. 4:02from database so suppose you want to get
87. 4:05records from database through linku okay
88. 4:08for that first you will uh first of you
89. 4:12you will use iable like this uh do not
90. 4:15worry about the linku and Lambda
91. 4:17expression here that I will explain in
92. 4:19other videos but you are understanding
93. 4:22this right here here we are getting the
94. 4:24records from the employees table where
95. 4:27the employees name start with h right
96. 4:30and you will get the filtered result in
97. 4:33this list e okay now the same result you
98. 4:36can get by using I queriable interface
99. 4:39also see the same query and you will get
100. 4:42the same result in list Q this time but
101. 4:46the point is I quable will take less
102. 4:49time as comparison to I numerable now
103. 4:52let me explain this
104. 4:54why if you use iable then first the
105. 4:58request will go to the database and
106. 5:00bring the whole data from the database
107. 5:03and then the filter the result at the
108. 5:06server side here so bringing the whole
109. 5:09data from the network will impact the
110. 5:11performance in a negative way right
111. 5:14because the data is too much okay on the
112. 5:17other hand if you use iable then the the
113. 5:22request will go to the database filter
114. 5:24the data then and there only and then
115. 5:27send back the filtered data data not the
116. 5:30whole data which is good for performance
117. 5:33because data is lesser the filter data
118. 5:35is lesser so that is the reason I
119. 5:38queriable is better than I enumerable
120. 5:41for SQL queries and database operation
121. 5:44all the points I have explain I have
122. 5:47said are written here only so that later
123. 5:50anyone can refer this uh PowerPoint and
124. 5:53for the revision
125. 5:54purpose one more point I variable is
126. 5:57under system. linku name space whereas
127. 6:00iable is under system. collections name
128. 6:04space that is all about I nameable and I
129. 6:07quable
130. 6:09[Music]