1 00:00:05,100 --> 00:00:06,150 So now that we've actually seen 2 00:00:06,150 --> 00:00:08,070 how to use the SQL language 3 00:00:08,070 --> 00:00:10,390 to work with SQLites databases, 4 00:00:10,390 --> 00:00:13,140 it's time to see how to do that in Python. 5 00:00:13,140 --> 00:00:16,630 So the Python SQLite3 module that's included with Python 6 00:00:16,630 --> 00:00:18,290 makes it really easy to create 7 00:00:18,290 --> 00:00:20,450 and use SQLite databases. 8 00:00:20,450 --> 00:00:22,050 So let's actually start off by creating 9 00:00:22,050 --> 00:00:24,130 this simple contacts database 10 00:00:24,130 --> 00:00:26,790 that we used in the SQL introduction. 11 00:00:26,790 --> 00:00:28,870 So I'm gonna create a new project here, 12 00:00:28,870 --> 00:00:31,390 Python project, obviously. 13 00:00:31,390 --> 00:00:34,720 And I'm going to call this one createDB. 14 00:00:39,050 --> 00:00:41,620 All right, and I'm going to create a new Python file 15 00:00:41,620 --> 00:00:45,160 by right-clicking the project, new Python file, 16 00:00:45,160 --> 00:00:47,910 and we'll call this one contacts. 17 00:00:49,180 --> 00:00:52,540 And we'll just go full screen here. 18 00:00:52,540 --> 00:00:53,880 Okay. 19 00:00:53,880 --> 00:00:57,010 So we start, going to start by importing the SQLite3 module, 20 00:00:57,010 --> 00:00:58,980 so we type import SQLite, 21 00:00:58,980 --> 00:01:01,010 and you can see that IntelliJ's found it for us, 22 00:01:01,010 --> 00:01:03,420 so we'll use the one that they recommend. 23 00:01:03,420 --> 00:01:05,970 Then we wanna create a connexion to the database. 24 00:01:05,970 --> 00:01:08,890 We'll do db equals sqlite3.connect. 25 00:01:10,970 --> 00:01:15,260 And we're gonna call this one contacts.sqlite. 26 00:01:15,260 --> 00:01:16,740 Now, I've said previously, 27 00:01:16,740 --> 00:01:19,370 that SQLite doesn't care what you call your database, 28 00:01:19,370 --> 00:01:22,250 as long as it's a valid file name, of course, 29 00:01:22,250 --> 00:01:23,970 but there's actually a reason here 30 00:01:23,970 --> 00:01:26,040 why I've used .sqlite as the name, 31 00:01:26,040 --> 00:01:28,140 and we'll see why that is later. 32 00:01:28,140 --> 00:01:32,620 So this line will create the contacts.sqlite database, 33 00:01:32,620 --> 00:01:34,050 if it doesn't already exist. 34 00:01:34,050 --> 00:01:36,290 Otherwise, it will open it for us. 35 00:01:36,290 --> 00:01:37,700 All right, so on the next line, now, 36 00:01:37,700 --> 00:01:39,880 we need to create a table, 37 00:01:39,880 --> 00:01:42,110 and we do that by passing a SQLite statement 38 00:01:42,110 --> 00:01:44,750 to the connexions execute function. 39 00:01:44,750 --> 00:01:45,920 So db.execute, 40 00:01:47,930 --> 00:01:49,080 then we type our SQL. 41 00:01:49,080 --> 00:01:51,160 So create table contacts, 42 00:01:54,620 --> 00:01:55,960 and left parentheses, 43 00:01:55,960 --> 00:01:58,080 we need a name and a type for each of the three fields. 44 00:01:58,080 --> 00:02:01,190 So name, space, text, comma, 45 00:02:01,190 --> 00:02:03,610 phone, space, integer, comma, 46 00:02:04,530 --> 00:02:07,710 and the last one's email, just text. 47 00:02:07,710 --> 00:02:11,150 The right parentheses, and then close the line off. 48 00:02:11,150 --> 00:02:13,310 All right, and we can do the similar thing 49 00:02:13,310 --> 00:02:15,810 by typing db.execute. 50 00:02:15,810 --> 00:02:17,950 This time we can use that to insert a line 51 00:02:17,950 --> 00:02:18,850 instead of record rows. 52 00:02:18,850 --> 00:02:20,680 Insert into, contacts, 53 00:02:24,410 --> 00:02:26,670 where we will put our three fields 54 00:02:26,670 --> 00:02:28,650 in parentheses, separated by commas. 55 00:02:28,650 --> 00:02:31,650 So name, obviously, phone. 56 00:02:31,650 --> 00:02:32,770 IntelliJ's trying to be helpful, 57 00:02:32,770 --> 00:02:35,320 but in this case, it's not really able to do much, 58 00:02:35,320 --> 00:02:39,250 because these values aren't coming from anywhere. 59 00:02:39,250 --> 00:02:40,630 And then values, but noticing 60 00:02:40,630 --> 00:02:42,290 how it's giving us the SQL here, 61 00:02:42,290 --> 00:02:44,270 so values, which is pretty cool. 62 00:02:44,270 --> 00:02:47,240 They want a parentheses, a parentheses here. 63 00:02:47,240 --> 00:02:48,420 They wanna use single quotes here, 64 00:02:48,420 --> 00:02:52,420 because we've got this string already using double quotes. 65 00:02:52,420 --> 00:02:54,830 So we need to, 6545678 there, 66 00:02:57,090 --> 00:02:58,930 and say tim@email.com. 67 00:03:01,210 --> 00:03:02,930 We need to make sure we've got a single quote, 68 00:03:02,930 --> 00:03:05,300 parentheses, a right parentheses, that is, 69 00:03:05,300 --> 00:03:09,460 double quote, and then right parentheses, which we have. 70 00:03:10,580 --> 00:03:13,050 And that should've been like that. 71 00:03:13,050 --> 00:03:15,480 All right, so that's our first line there to, 72 00:03:15,480 --> 00:03:18,600 could now insert a record into the contacts table. 73 00:03:18,600 --> 00:03:19,590 Now I'm gonna insert another row, 74 00:03:19,590 --> 00:03:21,750 but this time, watch what happens as I type. 75 00:03:21,750 --> 00:03:25,170 So db.execute, and double quotes, insert. 76 00:03:26,760 --> 00:03:29,010 Now, what should happen, which does sometimes, 77 00:03:29,010 --> 00:03:32,380 is the IntelliJ lookup will actually start helping us 78 00:03:32,380 --> 00:03:35,150 by giving the, sort of giving us some hints 79 00:03:35,150 --> 00:03:36,620 as to what commands to use, 80 00:03:36,620 --> 00:03:37,450 but you can see in this case, 81 00:03:37,450 --> 00:03:39,460 it hasn't done anything at this point for us, 82 00:03:39,460 --> 00:03:40,470 which isn't very nice. 83 00:03:40,470 --> 00:03:42,480 I thought it might kick in and do that for us, 84 00:03:42,480 --> 00:03:43,870 but we'll try typing a bit more 85 00:03:43,870 --> 00:03:45,860 and see whether it comes back into play again. 86 00:03:45,860 --> 00:03:47,860 So insert into contacts. 87 00:03:49,400 --> 00:03:50,470 Now that was actually trying to give us 88 00:03:50,470 --> 00:03:52,200 the SQL command there, that lookup, 89 00:03:52,200 --> 00:03:54,740 but if I keep typing, 90 00:03:54,740 --> 00:03:58,900 and we'll just go with the three fields, name, phone. 91 00:03:58,900 --> 00:04:00,920 Actually, this time what we'll do, 92 00:04:00,920 --> 00:04:02,840 let's just delete that. 93 00:04:04,570 --> 00:04:06,140 And put a space and put values, 94 00:04:06,140 --> 00:04:08,390 and noticing how it's come up and 95 00:04:08,390 --> 00:04:11,390 put in the keyword values for us automatically. 96 00:04:11,390 --> 00:04:13,960 And I'll just enter the values that we wanna use here, 97 00:04:13,960 --> 00:04:17,540 which will be Brian in single quotes, 1234, 98 00:04:19,760 --> 00:04:22,680 and brian@myemail, email.com again, 99 00:04:25,260 --> 00:04:27,570 separated by single parentheses, 100 00:04:27,570 --> 00:04:29,500 and the whole thing's got parentheses around it 101 00:04:29,500 --> 00:04:30,450 for the value statement, 102 00:04:30,450 --> 00:04:32,800 and then we've got a double quote to close off the string 103 00:04:32,800 --> 00:04:36,890 and a right parentheses to close off the execute function. 104 00:04:36,890 --> 00:04:38,890 Now, we're probably seeing some warnings over here, 105 00:04:38,890 --> 00:04:41,590 so we come over and have a look. 106 00:04:41,590 --> 00:04:44,220 No data sources are configured. 107 00:04:44,220 --> 00:04:47,260 Basically, IntelliJ doesn't have a schema for our database, 108 00:04:47,260 --> 00:04:48,520 so it can't recognise the names 109 00:04:48,520 --> 00:04:49,990 of the columns that we're using, 110 00:04:49,990 --> 00:04:51,980 but don't worry about these warnings for the moment. 111 00:04:51,980 --> 00:04:54,490 We'll come back to those a little bit later. 112 00:04:54,490 --> 00:04:55,740 The last thing I wanna do now, 113 00:04:55,740 --> 00:04:58,170 before we actually run this programme for the first time, 114 00:04:58,170 --> 00:05:01,110 is to close off our database connexions. 115 00:05:01,110 --> 00:05:05,110 We do that with db.close on line eight, like so. 116 00:05:06,020 --> 00:05:07,410 All right, so it should be we've got no errors, 117 00:05:07,410 --> 00:05:08,990 which we haven't, on the screen here. 118 00:05:08,990 --> 00:05:10,820 We can actually run this programme now, 119 00:05:10,820 --> 00:05:12,300 and we should have a table created 120 00:05:12,300 --> 00:05:14,730 with two rows added. 121 00:05:14,730 --> 00:05:16,820 Then we're gonna run it. 122 00:05:16,820 --> 00:05:17,750 We don't get any output, 123 00:05:17,750 --> 00:05:20,770 which is generally a good sign with MySQL 124 00:05:20,770 --> 00:05:21,650 that things have worked. 125 00:05:21,650 --> 00:05:23,180 And I'll just put this down the bottom, 126 00:05:23,180 --> 00:05:25,450 so we can see the output. 127 00:05:25,450 --> 00:05:28,550 All right, so looks like things have worked okay there. 128 00:05:28,550 --> 00:05:31,770 And to verify it, we could switch over to a terminal 129 00:05:31,770 --> 00:05:34,180 and use the SQLite3 command line shell 130 00:05:34,180 --> 00:05:35,320 to check the database, 131 00:05:35,320 --> 00:05:37,120 but we've already seen how to do that, 132 00:05:37,120 --> 00:05:41,500 so let's actually see how to query our database from Python. 133 00:05:41,500 --> 00:05:43,290 Now, there's two ways we can do that. 134 00:05:43,290 --> 00:05:45,800 The usual way, and the way that's common to other languages, 135 00:05:45,800 --> 00:05:49,300 such as Java, for example, is to use a cursor. 136 00:05:49,300 --> 00:05:51,280 Now cursors can be very useful, 137 00:05:51,280 --> 00:05:53,080 so I'm gonna explain about them 138 00:05:53,080 --> 00:05:55,280 before showing you a shortcut way 139 00:05:55,280 --> 00:05:58,100 of doing some of the same things from our connexion. 140 00:05:58,100 --> 00:06:01,060 First, though, we've actually got a problem here. 141 00:06:01,060 --> 00:06:03,050 Now, we can't run the programme again, 142 00:06:03,050 --> 00:06:05,830 because the create table command's going to fail 143 00:06:05,830 --> 00:06:08,230 if we try to execute it again. 144 00:06:08,230 --> 00:06:09,580 Now, we could write code to check 145 00:06:09,580 --> 00:06:11,460 if the table already exists, 146 00:06:11,460 --> 00:06:14,420 but the SQL language has got a slightly different form 147 00:06:14,420 --> 00:06:15,690 of the create table command 148 00:06:15,690 --> 00:06:18,000 that actually copes with this situation. 149 00:06:18,000 --> 00:06:20,020 So we come up here to line four, 150 00:06:20,020 --> 00:06:23,840 and we actually put in some extra wording. 151 00:06:23,840 --> 00:06:25,970 So if, and notice how I've just typed I, 152 00:06:25,970 --> 00:06:27,600 and it's now helpfully saying, yeah, 153 00:06:27,600 --> 00:06:30,120 if not exists, I can press enter or tab there, 154 00:06:30,120 --> 00:06:32,660 and it helpfully adds that to our code. 155 00:06:32,660 --> 00:06:33,820 So as you can imagine, 156 00:06:33,820 --> 00:06:35,900 if the table doesn't already exist, 157 00:06:35,900 --> 00:06:37,200 it's going to create it, 158 00:06:37,200 --> 00:06:38,910 and if it does exist, 159 00:06:38,910 --> 00:06:40,640 it's going to not try and recreate it again, 160 00:06:40,640 --> 00:06:44,110 which is exactly what we want to actually happen here. 161 00:06:44,110 --> 00:06:46,020 All right, so now we can test our code. 162 00:06:46,020 --> 00:06:48,320 So I'm gonna add the code to create a cursor 163 00:06:48,320 --> 00:06:50,600 and use it to run a select query. 164 00:06:50,600 --> 00:06:51,740 And I'll also close the cursor 165 00:06:51,740 --> 00:06:53,890 when we're done with it, to be consistent. 166 00:06:53,890 --> 00:06:56,690 So let's actually start here on line eight. 167 00:06:56,690 --> 00:07:00,350 And we're gonna put cursor equals db.cursor. 168 00:07:02,200 --> 00:07:04,560 And then we want to execute a select query, 169 00:07:04,560 --> 00:07:06,470 so it's cursor.execute, 170 00:07:08,360 --> 00:07:11,720 noting how cursors are executed at db.execute now, 171 00:07:11,720 --> 00:07:15,550 and let's just do a select star from contacts. 172 00:07:17,880 --> 00:07:20,910 And then we can put for row 173 00:07:20,910 --> 00:07:23,580 in cursor, colon, and print row. 174 00:07:27,280 --> 00:07:30,280 And then we wanna do a cursor.close. 175 00:07:31,480 --> 00:07:35,290 All right, so if we run this programme now, 176 00:07:35,290 --> 00:07:37,200 we actually get our two rows printed, as you can see, 177 00:07:37,200 --> 00:07:40,770 on the bottom of the screen in the output window. 178 00:07:40,770 --> 00:07:42,770 Now each row is printed as a tuple 179 00:07:42,770 --> 00:07:44,970 containing a value for each of the columns 180 00:07:44,970 --> 00:07:46,260 in the database. 181 00:07:46,260 --> 00:07:49,060 Now, a database cursor is iterable, 182 00:07:49,060 --> 00:07:51,560 so we can just use a for loop to iterate over the cursor 183 00:07:51,560 --> 00:07:54,400 and print each row, as we've actually done. 184 00:07:54,400 --> 00:07:56,820 And what we could also do, if we wanted to, 185 00:07:56,820 --> 00:07:59,340 we can unpack the tuples as we go, 186 00:07:59,340 --> 00:08:02,140 so we could slightly change the syntax there. 187 00:08:02,140 --> 00:08:04,250 Instead of just for row in cursor, 188 00:08:04,250 --> 00:08:05,910 we can put for name, 189 00:08:07,920 --> 00:08:09,840 phone, email in cursor. 190 00:08:11,340 --> 00:08:14,600 And then we can do print name, 191 00:08:14,600 --> 00:08:16,680 print phone, print email. 192 00:08:20,000 --> 00:08:23,330 And then we can do a separator times 20. 193 00:08:25,190 --> 00:08:28,020 So if we run that revised programme, 194 00:08:28,940 --> 00:08:31,310 you can see we've got our records 195 00:08:31,310 --> 00:08:34,390 unpacked, down the bottom in the output window. 196 00:08:34,390 --> 00:08:35,600 Now one thing you may have noticed 197 00:08:35,600 --> 00:08:37,809 is that I'm not terminating the SQL commands 198 00:08:37,809 --> 00:08:39,630 with a semi-colon. 199 00:08:39,630 --> 00:08:40,970 Now, they're not generally needed 200 00:08:40,970 --> 00:08:43,980 when using the Python 3 SQLite3 module, 201 00:08:43,980 --> 00:08:47,810 and in keeping with the, with the Python philosophy, 202 00:08:47,810 --> 00:08:50,160 you'll find they're generally not used. 203 00:08:50,160 --> 00:08:52,120 In fact, they can often get in the way 204 00:08:52,120 --> 00:08:54,210 if you store a select statement in a string, 205 00:08:54,210 --> 00:08:56,940 and later concatenate a where clause at the end. 206 00:08:56,940 --> 00:08:58,160 You don't wanna have to search for 207 00:08:58,160 --> 00:08:59,800 and remove a trailing semi-colon 208 00:08:59,800 --> 00:09:02,000 at the end of the select statement. 209 00:09:02,000 --> 00:09:03,720 So my recommendation is generally, 210 00:09:03,720 --> 00:09:07,570 don't use semi-colons when using SQL in Python. 211 00:09:07,570 --> 00:09:08,440 (chuckles) I know at this point, 212 00:09:08,440 --> 00:09:10,060 I spent a couple of lectures 213 00:09:10,060 --> 00:09:12,290 getting you into the habit of actually using them, 214 00:09:12,290 --> 00:09:15,040 but they are needed when using SQL in most environments, 215 00:09:15,040 --> 00:09:17,380 so it was a good habit to develop generally, 216 00:09:17,380 --> 00:09:19,980 but you can now relax and stop adding semi-colons 217 00:09:19,980 --> 00:09:23,050 in your SQL statements in Python. 218 00:09:23,050 --> 00:09:26,840 Okay, so our cursor code uses the cursor's execute method 219 00:09:26,840 --> 00:09:29,990 to execute the SQL against the database 220 00:09:29,990 --> 00:09:31,250 and return something that behaves 221 00:09:31,250 --> 00:09:33,090 very much like a list. 222 00:09:33,090 --> 00:09:35,590 So we can iterate over it to process each row, 223 00:09:35,590 --> 00:09:38,480 but it's really not a list. 224 00:09:38,480 --> 00:09:40,860 And if you think about it, a database table 225 00:09:40,860 --> 00:09:43,670 could contain, you know, literally billions of rows. 226 00:09:43,670 --> 00:09:45,520 So if the cursor tried to load them all 227 00:09:45,520 --> 00:09:47,440 into a list in memory, 228 00:09:47,440 --> 00:09:50,410 it's highly likely we'd run out of memory. 229 00:09:50,410 --> 00:09:53,040 So a cursor is what's called a generator. 230 00:09:53,040 --> 00:09:55,860 Now, I'm not gonna go into detail about those now, 231 00:09:55,860 --> 00:09:58,510 but a generator is basically an iterable 232 00:09:58,510 --> 00:10:01,070 that works by generating the next value 233 00:10:01,070 --> 00:10:03,750 each time it's used in Python. 234 00:10:03,750 --> 00:10:06,100 You can create an iterable object 235 00:10:06,100 --> 00:10:09,790 that will return every single possible integer number. 236 00:10:09,790 --> 00:10:11,010 So you could count to infinity 237 00:10:11,010 --> 00:10:12,430 without running out of memory. 238 00:10:12,430 --> 00:10:14,280 Time may be against you, of course, 239 00:10:14,280 --> 00:10:16,880 but memory wouldn't be a problem. 240 00:10:16,880 --> 00:10:20,210 So when our code iterates over the cursor, 241 00:10:20,210 --> 00:10:22,330 it returns the next row from the database 242 00:10:22,330 --> 00:10:25,270 but doesn't actually keep track of previous rows. 243 00:10:25,270 --> 00:10:27,330 Now because it's not really a list, 244 00:10:27,330 --> 00:10:29,800 there's no way to go back to previous records, 245 00:10:29,800 --> 00:10:32,630 and that explains why this next bit of code 246 00:10:32,630 --> 00:10:35,080 doesn't do what we might expect. 247 00:10:35,080 --> 00:10:36,000 And to show you what I mean, 248 00:10:36,000 --> 00:10:39,270 I'm going to actually take a copy of our for loop 249 00:10:39,270 --> 00:10:41,580 up to and including the separator, 250 00:10:41,580 --> 00:10:45,300 and I'm gonna paste that down here, 251 00:10:45,300 --> 00:10:46,760 put another space there. 252 00:10:46,760 --> 00:10:48,260 So looking at this, this, well actually, 253 00:10:48,260 --> 00:10:50,260 let's just run it first. 254 00:10:51,960 --> 00:10:53,020 So it's looking at the output 255 00:10:53,020 --> 00:10:56,090 at the bottom of the screen there. 256 00:10:56,090 --> 00:10:59,170 You may have expected the rows to be printed out again, 257 00:10:59,170 --> 00:11:01,190 but when we get to the second for loop, 258 00:11:01,190 --> 00:11:04,390 the cursors actually run out of rows, so nothing's printed. 259 00:11:04,390 --> 00:11:06,760 The only way to get our cursor to start again 260 00:11:06,760 --> 00:11:09,140 is to actually run the query again. 261 00:11:09,140 --> 00:11:12,270 And what that does, it makes cursors very efficient 262 00:11:12,270 --> 00:11:14,250 when reading data from databases, 263 00:11:14,250 --> 00:11:15,620 because they don't use loads of memory 264 00:11:15,620 --> 00:11:17,510 storing all the records. 265 00:11:17,510 --> 00:11:18,800 Now, sometimes, you may actually want 266 00:11:18,800 --> 00:11:20,940 the entire dataset in a single list, 267 00:11:20,940 --> 00:11:22,340 and rather than using a for loop 268 00:11:22,340 --> 00:11:23,490 to build up your own list, 269 00:11:23,490 --> 00:11:26,480 you can actually use the fetchall method. 270 00:11:26,480 --> 00:11:27,530 All right, so I'm actually gonna delete 271 00:11:27,530 --> 00:11:29,770 that second for loop, 272 00:11:29,770 --> 00:11:32,220 'cause it's not actually doing anything. 273 00:11:32,220 --> 00:11:35,090 And let's actually go above that, that loop. 274 00:11:35,090 --> 00:11:37,400 We'll actually put a space here, actually, 275 00:11:37,400 --> 00:11:39,210 after the execute, anyway, to just 276 00:11:39,210 --> 00:11:40,830 free things up a little bit. 277 00:11:40,830 --> 00:11:42,980 But let's actually just add something to that again, 278 00:11:42,980 --> 00:11:45,480 and put print cursor.fetchall. 279 00:11:51,470 --> 00:11:54,890 All right, so now if I actually run this, 280 00:11:56,860 --> 00:11:59,220 you can see that the fetchall has returned a list 281 00:11:59,220 --> 00:12:02,570 containing a tuple for each row in the database. 282 00:12:02,570 --> 00:12:04,070 So it is possible to get all the rows 283 00:12:04,070 --> 00:12:05,980 from a database into a list, 284 00:12:05,980 --> 00:12:08,130 and then you can actually move backwards and forwards 285 00:12:08,130 --> 00:12:10,180 through the items in the list. 286 00:12:10,180 --> 00:12:11,430 Because all the data's being retrieved 287 00:12:11,430 --> 00:12:13,620 from the cursor by the fetchall method, 288 00:12:13,620 --> 00:12:16,730 our for loop, though, in this particular case, on line 13, 289 00:12:16,730 --> 00:12:18,650 hasn't got anything to print. 290 00:12:18,650 --> 00:12:20,330 Now, there's also a fetchone method 291 00:12:20,330 --> 00:12:23,460 that returns the next row in the cursor. 292 00:12:23,460 --> 00:12:24,510 And to get that to work, 293 00:12:24,510 --> 00:12:26,910 we'll have to come in out the call the fetchall. 294 00:12:26,910 --> 00:12:28,670 So we'll do that first. 295 00:12:28,670 --> 00:12:32,400 And then we can actually change our code a little bit, 296 00:12:32,400 --> 00:12:36,240 up here, and we can put print cursor.fetchone. 297 00:12:40,220 --> 00:12:42,980 Let's just duplicate that another two times. 298 00:12:42,980 --> 00:12:45,320 And if we actually run this, 299 00:12:46,690 --> 00:12:48,300 so you can see what happened there. 300 00:12:48,300 --> 00:12:51,000 The first two times, it returned what was the current row, 301 00:12:51,000 --> 00:12:52,470 then moved on to the next one, 302 00:12:52,470 --> 00:12:56,470 but the third call, call to fetchone, results in none, 303 00:12:56,470 --> 00:12:59,320 and that's because there's no rows left to fetch. 304 00:12:59,320 --> 00:13:01,410 So fetchone is quite useful, 305 00:13:01,410 --> 00:13:03,200 and we're gonna be using that a bit later, 306 00:13:03,200 --> 00:13:05,150 when we wanna retrieve a single row 307 00:13:05,150 --> 00:13:06,790 based on its ID. 308 00:13:06,790 --> 00:13:09,010 All right, so I'm gonna finish the video here now. 309 00:13:09,010 --> 00:13:10,510 In the next video, we're gonna look at that shortcut 310 00:13:10,510 --> 00:13:12,560 that I mentioned earlier in this video, 311 00:13:12,560 --> 00:13:14,350 so I'll see you in the next video.