1 00:00:02,280 --> 00:00:04,380 So, what's the problem? 2 00:00:04,380 --> 00:00:07,980 Why do we need such a database thing? 3 00:00:07,980 --> 00:00:10,550 Well, up to this point in the course, 4 00:00:10,550 --> 00:00:13,330 when we stored data permanently, 5 00:00:13,330 --> 00:00:16,900 we always stored it in files. 6 00:00:16,900 --> 00:00:19,480 We simply wrote data into a file, 7 00:00:19,480 --> 00:00:21,570 and when we needed that data, 8 00:00:21,570 --> 00:00:23,910 we read it from that file. 9 00:00:23,910 --> 00:00:25,620 That's what we did before, 10 00:00:25,620 --> 00:00:27,400 we write data to a file, 11 00:00:27,400 --> 00:00:29,810 we fetch data from a file. 12 00:00:29,810 --> 00:00:32,780 And then we might filter that fetched data 13 00:00:32,780 --> 00:00:35,770 for a specific ID for example, 14 00:00:35,770 --> 00:00:38,330 as we did it here for restaurants, 15 00:00:38,330 --> 00:00:41,320 where we then went through all the fetched restaurants 16 00:00:41,320 --> 00:00:43,360 to get a specific restaurant, 17 00:00:43,360 --> 00:00:46,250 but we always interacted with the file system 18 00:00:46,250 --> 00:00:47,750 just like that. 19 00:00:47,750 --> 00:00:49,860 Now, whilst that worked, 20 00:00:49,860 --> 00:00:53,450 it's not great because when we create data 21 00:00:53,450 --> 00:00:56,460 and we always replace the entire content of a file 22 00:00:56,460 --> 00:00:58,130 with the new data, 23 00:00:58,130 --> 00:01:01,120 or when we read data and we then always read 24 00:01:01,120 --> 00:01:05,099 the entire file content just to then loop through it 25 00:01:05,099 --> 00:01:07,670 and find a specific element. 26 00:01:07,670 --> 00:01:11,060 Or if we might want to update or delete data, 27 00:01:11,060 --> 00:01:11,950 and for that, 28 00:01:11,950 --> 00:01:16,050 we also read the entire content to then find the element 29 00:01:16,050 --> 00:01:17,960 we wanna update or delete, 30 00:01:17,960 --> 00:01:21,020 then update the entire data and write it back. 31 00:01:21,020 --> 00:01:23,180 If we always do it like this, 32 00:01:23,180 --> 00:01:25,700 then this is pretty inefficient 33 00:01:25,700 --> 00:01:29,120 because we always overwrite everything, 34 00:01:29,120 --> 00:01:31,790 we always read everything, 35 00:01:31,790 --> 00:01:33,100 and that of course, 36 00:01:33,100 --> 00:01:37,070 we're explore various simple demo projects and websites, 37 00:01:37,070 --> 00:01:41,210 but if our website grows and we have more and more data, 38 00:01:41,210 --> 00:01:45,500 that will simply lead to performance issues and our code 39 00:01:45,500 --> 00:01:48,023 will do unnecessarily much work. 40 00:01:48,980 --> 00:01:49,980 As a side note, 41 00:01:49,980 --> 00:01:51,910 the operations we see here, 42 00:01:51,910 --> 00:01:54,730 creating, reading, updating and deleting, 43 00:01:54,730 --> 00:01:58,020 are very common and therefore commonly referred 44 00:01:58,020 --> 00:02:00,660 to as CRUD operations. 45 00:02:00,660 --> 00:02:02,600 And you will see them over and over again 46 00:02:02,600 --> 00:02:04,350 throughout the course and especially, 47 00:02:04,350 --> 00:02:06,530 also throughout the next sections, 48 00:02:06,530 --> 00:02:08,323 which are about databases. 49 00:02:09,850 --> 00:02:11,480 But back to this problem here. 50 00:02:11,480 --> 00:02:12,660 It's pretty inefficient 51 00:02:12,660 --> 00:02:15,780 if we always work with all the data 52 00:02:15,780 --> 00:02:18,270 and it's not just inefficient because we work 53 00:02:18,270 --> 00:02:20,210 with too much data, 54 00:02:20,210 --> 00:02:23,480 because we could try to do that more efficiently. 55 00:02:23,480 --> 00:02:26,570 When working with files as we did it here, 56 00:02:26,570 --> 00:02:29,100 we don't have to read the entire file. 57 00:02:29,100 --> 00:02:31,880 We don't have to write the entire file. 58 00:02:31,880 --> 00:02:35,150 NodeJS and other programming languages 59 00:02:35,150 --> 00:02:39,400 give us tools that would allow us to read parts of a file 60 00:02:39,400 --> 00:02:42,250 or write two parts of a file. 61 00:02:42,250 --> 00:02:44,750 So, we could optimize that. 62 00:02:44,750 --> 00:02:45,583 But as I said, 63 00:02:45,583 --> 00:02:49,480 it's not just the inefficiency in our bulk operations 64 00:02:49,480 --> 00:02:51,110 that we have at the moment, 65 00:02:51,110 --> 00:02:53,210 but instead in addition, 66 00:02:53,210 --> 00:02:56,220 we can simply run into scalability issues 67 00:02:56,220 --> 00:02:58,039 as our data size grows, 68 00:02:58,039 --> 00:03:00,250 as we have more, more data. 69 00:03:00,250 --> 00:03:02,800 And if we have more and more requests 70 00:03:02,800 --> 00:03:04,350 coming into our server, 71 00:03:04,350 --> 00:03:06,450 we can also run into issues 72 00:03:06,450 --> 00:03:09,780 because we can have concurrent file access 73 00:03:09,780 --> 00:03:13,140 where because of 10 incoming requests, 74 00:03:13,140 --> 00:03:17,550 we try to write to exactly the same file 10 times 75 00:03:17,550 --> 00:03:19,870 at the same point of time. 76 00:03:19,870 --> 00:03:23,300 So, we could have multiple read and/or write operations 77 00:03:23,300 --> 00:03:27,190 targeting the same file at the exact same point of time. 78 00:03:27,190 --> 00:03:30,180 And that could cause us big issues 79 00:03:30,180 --> 00:03:34,030 where reading then fails or writing fails, 80 00:03:34,030 --> 00:03:37,890 or we accidentally overwrite data from another request 81 00:03:37,890 --> 00:03:40,080 because we have two requests coming in 82 00:03:40,080 --> 00:03:41,493 at the same point of time. 83 00:03:42,520 --> 00:03:44,110 And in addition, 84 00:03:44,110 --> 00:03:47,610 we also might overwhelm our computer, our system 85 00:03:47,610 --> 00:03:48,443 as a whole, 86 00:03:48,443 --> 00:03:50,140 or at least the file system 87 00:03:50,140 --> 00:03:55,020 if we have too many concurrent read and write operations. 88 00:03:55,020 --> 00:03:59,300 So, as our website grows and handles more and more visitors, 89 00:03:59,300 --> 00:04:01,660 we can face more and more issues 90 00:04:01,660 --> 00:04:03,990 if we store and retrieve data, 91 00:04:03,990 --> 00:04:06,350 as we did it up to this point. 92 00:04:06,350 --> 00:04:08,730 Therefore, that was great for getting started 93 00:04:08,730 --> 00:04:10,410 with backend development, 94 00:04:10,410 --> 00:04:12,680 but it's typically not how you would store 95 00:04:12,680 --> 00:04:16,079 and fetch your data in real websites. 96 00:04:16,079 --> 00:04:19,600 And that's where databases help us. 97 00:04:19,600 --> 00:04:22,230 That's why databases are super important, 98 00:04:22,230 --> 00:04:26,070 and part of basically any website you're building. 99 00:04:26,070 --> 00:04:30,570 Because database management systems or DBMS 100 00:04:30,570 --> 00:04:32,990 are simply software systems, 101 00:04:32,990 --> 00:04:36,130 so, software you install on some system, 102 00:04:36,130 --> 00:04:37,310 you could say, 103 00:04:37,310 --> 00:04:41,930 that are optimized for data storage tasks, 104 00:04:41,930 --> 00:04:42,960 under the hood, 105 00:04:42,960 --> 00:04:46,630 they will still store data and files at some point, 106 00:04:46,630 --> 00:04:48,850 but they do it in a way more efficient way, 107 00:04:48,850 --> 00:04:53,530 taking away all the heavy lifting of managing file access 108 00:04:53,530 --> 00:04:56,470 and concurrent read and write access from you, 109 00:04:56,470 --> 00:04:59,440 and allowing you to just work with your data 110 00:04:59,440 --> 00:05:02,350 without having to worry about how that data 111 00:05:02,350 --> 00:05:06,283 is then written to a file or how it's fetched from a file. 112 00:05:07,200 --> 00:05:09,530 So, database management systems 113 00:05:09,530 --> 00:05:13,420 help us by optimizing read-write access, 114 00:05:13,420 --> 00:05:16,260 by taking away that pain from us. 115 00:05:16,260 --> 00:05:18,850 They help us by simply optimizing 116 00:05:18,850 --> 00:05:21,470 how data is stored and retrieved 117 00:05:21,470 --> 00:05:23,350 to make that more efficient, 118 00:05:23,350 --> 00:05:26,740 and don't overwhelm our files system 119 00:05:26,740 --> 00:05:29,530 and they optimize data querying 120 00:05:29,530 --> 00:05:32,390 by helping us with rich queries, 121 00:05:32,390 --> 00:05:35,330 by giving us specific query languages 122 00:05:35,330 --> 00:05:38,530 that allow us to find specific pieces of data 123 00:05:38,530 --> 00:05:41,340 in a large chunk of data with these, 124 00:05:41,340 --> 00:05:43,570 so that we have to write less code 125 00:05:43,570 --> 00:05:46,100 for the same or even more work 126 00:05:46,100 --> 00:05:49,130 that we want to do in our website. 127 00:05:49,130 --> 00:05:51,430 And therefore, database management systems 128 00:05:51,430 --> 00:05:54,660 are a must use if you have a website 129 00:05:54,660 --> 00:05:57,703 where you are storing and fetching data. 130 00:05:58,750 --> 00:06:00,100 And turns out, 131 00:06:00,100 --> 00:06:03,590 that many websites do that in some form. 132 00:06:03,590 --> 00:06:06,480 Now, there are many database management systems 133 00:06:06,480 --> 00:06:07,550 you could use. 134 00:06:07,550 --> 00:06:10,910 There are many providers, free ones and paid ones, 135 00:06:10,910 --> 00:06:13,860 but there are two main kind of systems 136 00:06:13,860 --> 00:06:15,600 in the end that you can use. 137 00:06:15,600 --> 00:06:17,360 And then for each system, 138 00:06:17,360 --> 00:06:21,860 you'll have plenty of possible database software solutions 139 00:06:21,860 --> 00:06:22,870 to choose from, 140 00:06:22,870 --> 00:06:25,993 but there are two main kinds of databases in the end. 141 00:06:26,910 --> 00:06:31,260 And that would be relational database management systems, 142 00:06:31,260 --> 00:06:34,910 also often called SQL databases. 143 00:06:34,910 --> 00:06:39,900 And SQL often is translated with structured query language, 144 00:06:39,900 --> 00:06:43,760 which means that SQL stands for structured query language. 145 00:06:43,760 --> 00:06:45,060 And you can use that, 146 00:06:45,060 --> 00:06:47,360 but actually it's not coming from that. 147 00:06:47,360 --> 00:06:49,230 It's not an acronym for that. 148 00:06:49,230 --> 00:06:53,650 Instead, SQL originally was called Sequel written like this, 149 00:06:53,650 --> 00:06:58,560 and then it was just shortened to SQL basically. 150 00:06:58,560 --> 00:06:59,930 Now, that's just a side note. 151 00:06:59,930 --> 00:07:03,410 It is a programming language kind of, 152 00:07:03,410 --> 00:07:07,280 that is built for getting data from databases 153 00:07:07,280 --> 00:07:10,790 and storing data in databases or in general, 154 00:07:10,790 --> 00:07:12,450 a language for talking 155 00:07:12,450 --> 00:07:16,220 to such relational database management systems. 156 00:07:16,220 --> 00:07:17,620 That's what SQL is. 157 00:07:17,620 --> 00:07:20,630 And that is what we will learn from this course. 158 00:07:20,630 --> 00:07:23,520 But besides such SQL databases 159 00:07:23,520 --> 00:07:26,000 that use this programming language 160 00:07:26,000 --> 00:07:28,450 for fetching data and writing data, 161 00:07:28,450 --> 00:07:32,490 we also have non-relational database management systems, 162 00:07:32,490 --> 00:07:35,650 which typically are called NoSQL databases 163 00:07:35,650 --> 00:07:36,500 because there, 164 00:07:36,500 --> 00:07:38,640 you store your data differently. 165 00:07:38,640 --> 00:07:42,090 It's structured differently inside of the database 166 00:07:42,090 --> 00:07:46,520 and you don't use the SQL language for fetching your data 167 00:07:46,520 --> 00:07:48,070 or for writing your data, 168 00:07:48,070 --> 00:07:51,340 but instead, different query languages. 169 00:07:51,340 --> 00:07:53,970 And these are the two main kinds of systems. 170 00:07:53,970 --> 00:07:55,470 And in the next lectures, 171 00:07:55,470 --> 00:07:59,942 I'll walk you through the basics of these two systems, 172 00:07:59,942 --> 00:08:04,070 and I'll give you a first comparison of these two systems. 173 00:08:04,070 --> 00:08:05,560 In this course however, 174 00:08:05,560 --> 00:08:08,870 we'll then have entire sections for both systems 175 00:08:08,870 --> 00:08:12,280 so that you get a detailed introduction to both systems 176 00:08:12,280 --> 00:08:15,170 so that you can then also use either system 177 00:08:15,170 --> 00:08:17,253 for your upcoming websites.