1 00:00:02,110 --> 00:00:05,630 So we are able to save different snapshots, 2 00:00:05,630 --> 00:00:06,840 different commits, 3 00:00:06,840 --> 00:00:09,760 and by initializing a good repository, 4 00:00:09,760 --> 00:00:14,020 these commits are all part of a so-called branch. 5 00:00:14,020 --> 00:00:15,300 In our case here, 6 00:00:15,300 --> 00:00:19,720 the default branch is the so-called master branch. 7 00:00:19,720 --> 00:00:21,170 How can we see this? 8 00:00:21,170 --> 00:00:23,720 Well, first by running "git status", 9 00:00:23,720 --> 00:00:26,530 once again we know this command already. 10 00:00:26,530 --> 00:00:30,240 There you'll see that we are on the branch master here. 11 00:00:30,240 --> 00:00:31,400 And besides that, 12 00:00:31,400 --> 00:00:35,540 we also have a command which lists all the branches inside 13 00:00:35,540 --> 00:00:36,910 our Git project. 14 00:00:36,910 --> 00:00:39,897 And this command is simply "git branch". 15 00:00:40,940 --> 00:00:44,490 Git branch here doesn't show us well, too much information. 16 00:00:44,490 --> 00:00:46,980 We have one branch only. 17 00:00:46,980 --> 00:00:49,760 And currently we are in this branch. 18 00:00:49,760 --> 00:00:52,090 This is indicated by the green color here 19 00:00:52,090 --> 00:00:55,163 and by this asterisk ahead of the branch name. 20 00:00:56,180 --> 00:00:58,940 As we saw it, when running Git in it, 21 00:00:58,940 --> 00:01:03,270 we also have the ability to rename a branch. 22 00:01:03,270 --> 00:01:05,140 Typically and historically, 23 00:01:05,140 --> 00:01:09,950 the default branch inside a Git project was named "master". 24 00:01:09,950 --> 00:01:13,150 In the last months and years, this changed. 25 00:01:13,150 --> 00:01:17,890 Nowadays, we typically also use "main" instead of "master". 26 00:01:17,890 --> 00:01:19,750 We can of course change the name, 27 00:01:19,750 --> 00:01:21,570 we'll do this in a few seconds. 28 00:01:21,570 --> 00:01:24,920 It's just important to keep in mind that this master 29 00:01:24,920 --> 00:01:27,870 or main branch, typically is the branch 30 00:01:27,870 --> 00:01:31,550 holding your main code, your working code. 31 00:01:31,550 --> 00:01:32,650 For example, 32 00:01:32,650 --> 00:01:35,870 the code you use for your currently running website, 33 00:01:35,870 --> 00:01:36,870 for example. 34 00:01:36,870 --> 00:01:39,020 If you want to implement new features, 35 00:01:39,020 --> 00:01:41,960 you create new branches, work on that feature. 36 00:01:41,960 --> 00:01:42,900 Once you're done, 37 00:01:42,900 --> 00:01:45,980 you add these changes to the master branch. 38 00:01:45,980 --> 00:01:48,740 We'll of course have a look at this flow in this lecture. 39 00:01:48,740 --> 00:01:52,310 I just wanted to give you some insights already, 40 00:01:52,310 --> 00:01:55,160 what is going to happen to get a better idea 41 00:01:55,160 --> 00:01:57,693 of this branch concept immediately. 42 00:01:58,560 --> 00:02:02,280 Let's get started by renaming this branch, tho. 43 00:02:02,280 --> 00:02:05,850 Currently, we are inside the branch that we want to rename. 44 00:02:05,850 --> 00:02:08,030 So the master branch in our case, 45 00:02:08,030 --> 00:02:11,930 and if we now run "git branch -m", 46 00:02:11,930 --> 00:02:13,720 and now add the new name 47 00:02:13,720 --> 00:02:15,470 that we want to use for this branch, 48 00:02:15,470 --> 00:02:17,760 in our case, this could be "main". 49 00:02:17,760 --> 00:02:21,770 Well, by doing this, you get no confirmation at all, 50 00:02:21,770 --> 00:02:24,720 but if you then run "git branch", 51 00:02:24,720 --> 00:02:28,370 you'll see that "master" now changed to "main". 52 00:02:28,370 --> 00:02:31,250 This didn't have any kind of impact on through commits 53 00:02:31,250 --> 00:02:32,560 inside this branch. 54 00:02:32,560 --> 00:02:34,923 It was just a plain renaming. 55 00:02:36,020 --> 00:02:39,810 Now let's say that this content of this main branch here 56 00:02:39,810 --> 00:02:41,670 is exactly what you want to have. 57 00:02:41,670 --> 00:02:43,970 So you want to have this test or text file 58 00:02:43,970 --> 00:02:45,220 and the second commit, 59 00:02:45,220 --> 00:02:48,800 and now we want to add, well, additional data, 60 00:02:48,800 --> 00:02:51,600 but not immediately into this main branch. 61 00:02:51,600 --> 00:02:55,520 We first want to add this data, write some code, 62 00:02:55,520 --> 00:02:56,530 test the code. 63 00:02:56,530 --> 00:03:00,000 And then once it's done, we want to implement this code 64 00:03:00,000 --> 00:03:03,873 into this main branch, into our main project, so to say. 65 00:03:04,730 --> 00:03:07,660 What we need for this is a new branch. 66 00:03:07,660 --> 00:03:09,980 And to create new branches in Git, 67 00:03:09,980 --> 00:03:12,220 we have a, well, command obviously, 68 00:03:12,220 --> 00:03:16,210 and this command is called "git checkout". 69 00:03:16,210 --> 00:03:19,770 Checkout here simply means we refer to another branch. 70 00:03:19,770 --> 00:03:23,310 Checkout can also be used to switch between branches. 71 00:03:23,310 --> 00:03:26,680 In our case, not possible as we only have a single branch 72 00:03:26,680 --> 00:03:28,460 only at the moment. 73 00:03:28,460 --> 00:03:29,547 And now with " -b", 74 00:03:30,390 --> 00:03:33,460 this simply means that we want to check out a new branch 75 00:03:33,460 --> 00:03:36,990 and create a new branch based on the branch 76 00:03:36,990 --> 00:03:38,340 we are currently in. 77 00:03:38,340 --> 00:03:40,620 So based on our main branch here, 78 00:03:40,620 --> 00:03:42,980 and now we can give this branch a name. 79 00:03:42,980 --> 00:03:45,710 There is no strict naming convention here. 80 00:03:45,710 --> 00:03:48,540 In my case, I'll simply call it "feature", 81 00:03:48,540 --> 00:03:51,470 as this branch will add a new feature 82 00:03:51,470 --> 00:03:54,040 to our main branch in the end. 83 00:03:54,040 --> 00:03:57,000 With this command, you get the confirmation 84 00:03:57,000 --> 00:04:00,800 that we switched to a new branch, named "feature" 85 00:04:00,800 --> 00:04:03,163 and by running "git branch" now, 86 00:04:04,800 --> 00:04:08,280 you'll see that we are already in this feature branch. 87 00:04:08,280 --> 00:04:12,120 Again, indicated by the green color and that asterisk. 88 00:04:12,120 --> 00:04:16,240 And if we check the commits inside this feature branch 89 00:04:16,240 --> 00:04:18,177 with "git log", 90 00:04:20,209 --> 00:04:22,660 well, you see no difference, right? 91 00:04:22,660 --> 00:04:24,870 We are still having the same commits 92 00:04:24,870 --> 00:04:27,040 that we had in the main branch, 93 00:04:27,040 --> 00:04:29,350 and you also get the information up here that, 94 00:04:29,350 --> 00:04:30,250 well basically, 95 00:04:30,250 --> 00:04:33,600 this commit with this ID is the head. 96 00:04:33,600 --> 00:04:36,010 The head is so to say the latest commit 97 00:04:36,010 --> 00:04:37,520 of a specific branch. 98 00:04:37,520 --> 00:04:40,540 So this commit is the head of both the feature 99 00:04:40,540 --> 00:04:41,823 and the main branch. 100 00:04:42,720 --> 00:04:45,970 With this now we can work on code as I said, 101 00:04:45,970 --> 00:04:48,590 that we might want to implement in this feature branch. 102 00:04:48,590 --> 00:04:51,210 Here I'll keep things simple again, 103 00:04:51,210 --> 00:04:53,860 as this module is just about understanding 104 00:04:53,860 --> 00:04:55,980 how Git generally works. 105 00:04:55,980 --> 00:05:00,077 Therefore we could create a new folder and let's say, 106 00:05:00,077 --> 00:05:02,523 "new feature", for example. 107 00:05:03,500 --> 00:05:08,500 And in there, we simply add the "feature.txt" file. 108 00:05:08,550 --> 00:05:11,230 So this is content that we now only have 109 00:05:11,230 --> 00:05:13,070 in our feature branch. 110 00:05:13,070 --> 00:05:16,343 So if you now run "git status" once again, 111 00:05:18,090 --> 00:05:20,600 you see we are on the feature branch, 112 00:05:20,600 --> 00:05:23,490 that's important, and we have untracked files. 113 00:05:23,490 --> 00:05:26,390 So we basically have this new feature folder and all the 114 00:05:26,390 --> 00:05:28,220 files it contains. 115 00:05:28,220 --> 00:05:32,463 Therefore, we can now run again "git add . " 116 00:05:33,590 --> 00:05:36,650 to add all newly added files 117 00:05:36,650 --> 00:05:39,450 and changes made to tracked files. 118 00:05:39,450 --> 00:05:41,010 And now we commit this change 119 00:05:41,010 --> 00:05:46,010 with "git commit -m "added mew feature"". 120 00:05:48,640 --> 00:05:52,460 Like this, the commit was successful. 121 00:05:52,460 --> 00:05:55,490 If we check our log, once again, 122 00:05:55,490 --> 00:06:00,060 you see we have three commits now in our feature branch, 123 00:06:00,060 --> 00:06:02,940 but only two commits in our main branch. 124 00:06:02,940 --> 00:06:04,830 You can again see this by this head. 125 00:06:04,830 --> 00:06:08,060 So here, the latest commit is in the feature branch, 126 00:06:08,060 --> 00:06:09,210 this one here. 127 00:06:09,210 --> 00:06:10,710 Whereas the second commit, 128 00:06:10,710 --> 00:06:12,640 so this one we created earlier, 129 00:06:12,640 --> 00:06:15,680 is part of the main branch only. 130 00:06:15,680 --> 00:06:16,860 And now the question is, 131 00:06:16,860 --> 00:06:19,970 how can we bring these changes together? 132 00:06:19,970 --> 00:06:21,910 How can we add this feature, 133 00:06:21,910 --> 00:06:26,610 this commit added in the feature branch, to our main branch? 134 00:06:26,610 --> 00:06:30,033 Well, for this, we first leave our log with Q once again, 135 00:06:30,910 --> 00:06:35,120 and then we have to merge the two branches. 136 00:06:35,120 --> 00:06:37,810 Merging branches simply means you combine 137 00:06:37,810 --> 00:06:40,060 the two commits of these branches. 138 00:06:40,060 --> 00:06:43,050 Well, to have a merged branch with all the code 139 00:06:43,050 --> 00:06:46,770 implemented or incorporated in this branch. 140 00:06:46,770 --> 00:06:49,017 Merging always works from a 141 00:06:49,017 --> 00:06:52,810 "I am currently in a branch that should receive 142 00:06:52,810 --> 00:06:55,350 additional commits", way of thinking. 143 00:06:55,350 --> 00:06:56,270 So in our case, 144 00:06:56,270 --> 00:07:00,240 this means that if we want to add the feature that we just 145 00:07:00,240 --> 00:07:03,670 edit in the feature branch to our master branch, 146 00:07:03,670 --> 00:07:06,810 we have to switch to the master branch first 147 00:07:06,810 --> 00:07:11,410 and then merge the feature branch into the master branch. 148 00:07:11,410 --> 00:07:15,550 To do that, we should check out our master branch therefore, 149 00:07:15,550 --> 00:07:17,787 so "git checkout master", 150 00:07:18,740 --> 00:07:21,460 which doesn't work as we renamed it to "main". 151 00:07:21,460 --> 00:07:22,680 So, my bad here. 152 00:07:22,680 --> 00:07:26,110 So we should of course refer to the main branch. 153 00:07:26,110 --> 00:07:27,420 Here we are. 154 00:07:27,420 --> 00:07:31,680 Now, you'll see in our git log that inside the main branch 155 00:07:31,680 --> 00:07:33,523 we only have these two commits. 156 00:07:35,370 --> 00:07:39,690 But, by now running "git merge", 157 00:07:39,690 --> 00:07:44,160 and now referring to the branch that contains the commits 158 00:07:44,160 --> 00:07:47,230 that should be merged into our main branch here, 159 00:07:47,230 --> 00:07:49,410 so we run "git merge feature". 160 00:07:49,410 --> 00:07:52,190 So the branch name of the other branch. 161 00:07:52,190 --> 00:07:55,420 Well, if we do that, you see that now, 162 00:07:55,420 --> 00:07:58,660 although we are still in the master branch, 163 00:07:58,660 --> 00:08:00,690 we have this new feature folder 164 00:08:00,690 --> 00:08:04,890 an alternate text file added into this branch. 165 00:08:04,890 --> 00:08:07,057 And by again running "git log", 166 00:08:08,070 --> 00:08:11,210 this, you see that now again, 167 00:08:11,210 --> 00:08:15,510 both branches here main and feature are the so-called head, 168 00:08:15,510 --> 00:08:16,900 so in simple words, 169 00:08:16,900 --> 00:08:19,620 the latest commit of the branches, 170 00:08:19,620 --> 00:08:21,250 and therefore this feature 171 00:08:21,250 --> 00:08:25,490 is now available while also in this main branch. 172 00:08:25,490 --> 00:08:28,120 So this was a successful merge, 173 00:08:28,120 --> 00:08:31,110 but what happens if we accidentally work 174 00:08:31,110 --> 00:08:34,900 on the same code section, on the same code snapshot 175 00:08:34,900 --> 00:08:38,559 in the same file and then we try to run such a merge? 176 00:08:38,559 --> 00:08:40,530 This would obviously lead to a conflict 177 00:08:40,530 --> 00:08:43,700 because we have changes applied to the same well, 178 00:08:43,700 --> 00:08:45,710 position so to say in our code, 179 00:08:45,710 --> 00:08:49,020 and then we have to decide, well, which change wins. 180 00:08:49,020 --> 00:08:50,863 So which change should be kept. 181 00:08:51,720 --> 00:08:53,790 We are currently in the master branch, 182 00:08:53,790 --> 00:08:58,790 therefore we could go to our "test.txt" file. 183 00:08:59,920 --> 00:09:02,160 And we could say that we, don't call this. 184 00:09:02,160 --> 00:09:03,210 This is my first commit. 185 00:09:03,210 --> 00:09:08,210 But this is another commit here, right? Like this. 186 00:09:09,770 --> 00:09:13,700 So we then add this and commit this change 187 00:09:13,700 --> 00:09:18,693 with a message of "updated test.txt" . 188 00:09:22,400 --> 00:09:23,290 So we did that. 189 00:09:23,290 --> 00:09:25,013 And if we now check our log, 190 00:09:26,840 --> 00:09:29,370 you see that we have well, a new commit in here, 191 00:09:29,370 --> 00:09:32,670 updated test.txt in our main branch, 192 00:09:32,670 --> 00:09:35,400 which doesn't affect the feature branch at the moment. 193 00:09:35,400 --> 00:09:37,840 So we can leave the log again 194 00:09:37,840 --> 00:09:40,433 and now check out the feature branch. 195 00:09:44,810 --> 00:09:46,630 Let me clear this. 196 00:09:46,630 --> 00:09:48,930 And here we still have the initial stage, right? 197 00:09:48,930 --> 00:09:50,630 So the unchanged text. 198 00:09:50,630 --> 00:09:52,517 And now we say, well, 199 00:09:52,517 --> 00:09:57,517 "this is again a commit", just to have a difference here. 200 00:09:59,320 --> 00:10:01,550 So we save this now. 201 00:10:01,550 --> 00:10:04,720 We also add this change to the staging area. 202 00:10:04,720 --> 00:10:08,410 We commit this change inside our feature branch, 203 00:10:08,410 --> 00:10:13,410 maybe with "changed test.txt content" 204 00:10:14,923 --> 00:10:17,870 to have a different message here. 205 00:10:17,870 --> 00:10:20,220 So we commit this. No problem here. 206 00:10:20,220 --> 00:10:22,833 If in a run, our git log once again, 207 00:10:25,100 --> 00:10:26,230 we see that this is all right. 208 00:10:26,230 --> 00:10:29,713 So feature branch has this latest commit we just added. 209 00:10:30,940 --> 00:10:34,973 And if we now, again, check out our master branch, 210 00:10:36,666 --> 00:10:39,120 and again, my bad, I'm sorry about this. 211 00:10:39,120 --> 00:10:40,810 I typically work with "master" still, 212 00:10:40,810 --> 00:10:43,630 therefore I'm not totally used to "main" here. 213 00:10:43,630 --> 00:10:45,547 So "git checkout main". 214 00:10:46,470 --> 00:10:47,830 Clear it. 215 00:10:47,830 --> 00:10:50,370 Now we again, run our merge command. 216 00:10:50,370 --> 00:10:53,760 So "git merge" and we merged a feature branch 217 00:10:53,760 --> 00:10:55,850 into our main or master branch. 218 00:10:55,850 --> 00:10:57,957 So "git merged feature". 219 00:10:59,450 --> 00:11:02,860 Then we see that we have well emerged conflict 220 00:11:03,770 --> 00:11:06,670 because we have a current change. 221 00:11:06,670 --> 00:11:09,320 This is the change we have in our current branch. 222 00:11:09,320 --> 00:11:10,153 So in our case, 223 00:11:10,153 --> 00:11:13,840 the main branch, and we have an incoming change. 224 00:11:13,840 --> 00:11:16,740 This is the change that we made in the feature branch. 225 00:11:16,740 --> 00:11:21,120 So the branch that we want to merge into this master branch, 226 00:11:21,120 --> 00:11:22,990 and therefore we have well, 227 00:11:22,990 --> 00:11:26,120 multiple options to fix this merge conflict. 228 00:11:26,120 --> 00:11:29,180 Visual studio code is a great help here, by the way. 229 00:11:29,180 --> 00:11:30,730 And well basically, 230 00:11:30,730 --> 00:11:33,620 the most common things we do is either compare the 231 00:11:33,620 --> 00:11:37,190 changes over here, or we accept the current change. 232 00:11:37,190 --> 00:11:41,010 So the change in our current branch or the incoming change. 233 00:11:41,010 --> 00:11:43,813 So as I said, the change from the feature branch here. 234 00:11:44,680 --> 00:11:47,660 If we accept that incoming change here, for example, 235 00:11:47,660 --> 00:11:49,670 we can simply click right here 236 00:11:49,670 --> 00:11:52,040 and then we see if we still have a warning. 237 00:11:52,040 --> 00:11:57,040 So, if we save this now and run "git status", 238 00:12:00,900 --> 00:12:03,430 you see we have unmerged paths because 239 00:12:03,430 --> 00:12:05,230 that was the problem that we have. 240 00:12:05,230 --> 00:12:07,890 But now with the accepted incoming change 241 00:12:07,890 --> 00:12:09,770 and saving the file, 242 00:12:09,770 --> 00:12:11,700 we need to create another commit. 243 00:12:11,700 --> 00:12:12,830 So let's run "git add", 244 00:12:12,830 --> 00:12:15,987 and let's now commit this change with a message of 245 00:12:15,987 --> 00:12:20,987 "merged text.txt from feature", for example, 246 00:12:24,910 --> 00:12:29,910 and with this, now clear this once again and run "git log". 247 00:12:32,390 --> 00:12:33,600 You see that in here, 248 00:12:33,600 --> 00:12:36,530 we now have the latest commit from the feature branch. 249 00:12:36,530 --> 00:12:39,110 So this is now part of our main branch. 250 00:12:39,110 --> 00:12:40,280 And additionally, 251 00:12:40,280 --> 00:12:41,770 we have that merge commit. 252 00:12:41,770 --> 00:12:44,400 So this is basically the commit that we just created 253 00:12:44,400 --> 00:12:46,860 that brought these two branches together 254 00:12:46,860 --> 00:12:51,510 without any conflicts as we just, well solved these. 255 00:12:51,510 --> 00:12:54,380 So, this is it about creating commits 256 00:12:54,380 --> 00:12:57,670 and creating branches and merging branches. 257 00:12:57,670 --> 00:13:01,680 Now, the next question is, how can we actually delete data? 258 00:13:01,680 --> 00:13:05,270 So delete commits, delete branches and so on. 259 00:13:05,270 --> 00:13:08,083 This is how we will continue in the next lecture.