1 00:00:00,300 --> 00:00:03,060 Let's select everything from our books table again. 2 00:00:03,060 --> 00:00:07,740 We have an ID, which is a unique identifier for the database entry. 3 00:00:07,740 --> 00:00:12,590 This is a common practice and guarantees that every row is not a duplicate of 4 00:00:12,590 --> 00:00:16,910 another, and can be isolated from all other rows if needed. 5 00:00:16,910 --> 00:00:22,820 We have the title, author, genre, and first in school published. 6 00:00:22,820 --> 00:00:26,140 Remember, querying a table's contents allows us to present 7 00:00:26,140 --> 00:00:29,030 the results of a database in many different ways. 8 00:00:29,030 --> 00:00:32,070 The results are designed for humans to read. 9 00:00:32,070 --> 00:00:35,270 But sometimes the column names aren't that friendly. 10 00:00:35,270 --> 00:00:38,980 Let's say I was running a query for the library administrator. 11 00:00:38,980 --> 00:00:42,624 They want a report of all the books in the database along with the year that they 12 00:00:42,624 --> 00:00:43,759 were first published. 13 00:00:47,642 --> 00:00:50,870 The column headers are all in lower case. 14 00:00:50,870 --> 00:00:53,140 This may be distracting to the report reader. 15 00:00:53,140 --> 00:00:58,190 We can change the title of any column, by using the keyword, as. 16 00:00:58,190 --> 00:01:02,770 After the as, you can write what you want to alias the column name to. 17 00:01:02,770 --> 00:01:05,370 Let's use Title with an uppercase T. 18 00:01:06,530 --> 00:01:10,340 When we run the query now we get the results back with a capital T 19 00:01:10,340 --> 00:01:12,300 in the titles column. 20 00:01:12,300 --> 00:01:15,551 How about the first underscore publish column? 21 00:01:15,551 --> 00:01:20,970 We can use the as keyword again but with the words first published. 22 00:01:23,570 --> 00:01:26,178 If you try and execute this query, you'll get an error. 23 00:01:26,178 --> 00:01:29,240 Error: near "Published": syntax error. 24 00:01:29,240 --> 00:01:33,210 The key for us here is that it's a syntax error. 25 00:01:33,210 --> 00:01:35,420 Remember the syntax is the grammar or 26 00:01:35,420 --> 00:01:39,140 the rules surrounding the way we write programming code. 27 00:01:39,140 --> 00:01:42,500 The computer doesn't understand the word Published. 28 00:01:42,500 --> 00:01:47,890 It's expecting a from or a comma, followed by another column name. 29 00:01:47,890 --> 00:01:51,380 We can't use multiple words like this when writing sequel queries. 30 00:01:52,570 --> 00:01:57,980 So what do we do for something such our first published dailies, in our reports? 31 00:01:57,980 --> 00:02:00,510 There is a way we can use some punctuation, 32 00:02:00,510 --> 00:02:03,910 which is part of the sequel syntax, to solve this problem. 33 00:02:03,910 --> 00:02:10,407 We can define column names with spaces by wrapping them in quotes like this. 34 00:02:10,407 --> 00:02:13,601 The opening quote is just before the first letter, and 35 00:02:13,601 --> 00:02:16,040 the closing quote after the last letter. 36 00:02:17,740 --> 00:02:19,380 But here's another got ya. 37 00:02:19,380 --> 00:02:22,840 Writing SQL in different databases like Microsoft SQL, or 38 00:02:22,840 --> 00:02:28,610 PostgreSQL my require you to use different punctuation for writing aliases. 39 00:02:28,610 --> 00:02:32,870 Some require single quotes, others even require square brackets. 40 00:02:32,870 --> 00:02:38,360 The SQL we're using in SQL Playground can use double quotes, but just be mindful. 41 00:02:38,360 --> 00:02:43,700 SQL in different settings may have these slight variations in syntax. 42 00:02:43,700 --> 00:02:47,512 Most database documentations have help to guide you around these difficulties. 43 00:02:47,512 --> 00:02:51,360 When we execute this query now, we see title and 44 00:02:51,360 --> 00:02:55,590 first published with a space as the column titles. 45 00:02:55,590 --> 00:02:59,973 There is a short hand for this syntax, where you remove the as keyword. 46 00:03:02,749 --> 00:03:05,672 You can try it too. 47 00:03:05,672 --> 00:03:06,472 See? 48 00:03:06,472 --> 00:03:08,320 It's the same results. 49 00:03:08,320 --> 00:03:11,440 I avoid this syntax because it's not very clear. 50 00:03:11,440 --> 00:03:12,740 I just wanted to bring you up so 51 00:03:12,740 --> 00:03:15,730 you weren't confused if you saw it somewhere else. 52 00:03:15,730 --> 00:03:19,960 To recap, to alias a column name to something of your choosing, 53 00:03:19,960 --> 00:03:25,280 type SELECT the keyword AS, followed by the new name. 54 00:03:27,020 --> 00:03:32,230 So, if I were to bring back all patron names in a more user-friendly format, 55 00:03:32,230 --> 00:03:34,080 I could do something like this. 56 00:03:34,080 --> 00:03:39,048 With quotes around the first name and last name. 57 00:03:42,860 --> 00:03:46,430 These characters surrounded by quote marks are called strings. 58 00:03:46,430 --> 00:03:48,450 Meaning strings of characters. 59 00:03:48,450 --> 00:03:52,310 Letters, numbers, special characters and spaces. 60 00:03:52,310 --> 00:03:55,070 One final notes about the as keyword. 61 00:03:55,070 --> 00:03:59,710 When you bring back data with a new label using the as keyword 62 00:03:59,710 --> 00:04:03,370 it does not change the name of the column in the actual database. 63 00:04:03,370 --> 00:04:07,680 For example, when we aliased our first underscore published column 64 00:04:07,680 --> 00:04:10,770 as first published in our report. 65 00:04:10,770 --> 00:04:14,380 The column name is always first_published. 66 00:04:14,380 --> 00:04:18,880 Only in our report do we see the column represented as First Published. 67 00:04:18,880 --> 00:04:22,220 This is why we call it an alias. 68 00:04:22,220 --> 00:04:27,230 As an aside, the as keyword can be used to alias table names for 69 00:04:27,230 --> 00:04:30,910 more complex queries working with multiple tables. 70 00:04:30,910 --> 00:04:33,060 We'll be covering that in another course.