-
Notifications
You must be signed in to change notification settings - Fork 0
/
02_where_ternary_rvs.sql
85 lines (78 loc) · 1.87 KB
/
02_where_ternary_rvs.sql
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
/*
Goal: learn about NULL & how to return rows that match a boolean expression with WHERE
Which campgrounds allow RVs?
Remember the full camp_example table from 00_create_camp_example:
+-------------------------+----------------------+---------------+
| name | campsites_reservable | is_rv_allowed |
+-------------------------+----------------------+---------------+
| 277 North Campground | 1 | |
| Abrams Creek Campground | 16 | 1 |
| Adirondack Shelters | 2 | 0 |
+-------------------------+----------------------+---------------+
Sqlite does not have a boolean type
We use:
- 1 for true
- 0 for false
- NULL (blank) for unknown
*/
/*
We don't know if 227 North Campground allows RVs
*/
SELECT
name
FROM
camp_example
WHERE
is_rv_allowed IS NULL;
-- result
-- +----------------------+
-- | name |
-- +----------------------+
-- | 277 North Campground |
-- +----------------------+
/*
We have NOT NULL (aka known) values for the other two campgrounds
*/
SELECT
name
FROM
camp_example
WHERE
is_rv_allowed IS NOT NULL;
-- result
-- +-------------------------+
-- | name |
-- +-------------------------+
-- | Abrams Creek Campground |
-- | Adirondack Shelters |
-- +-------------------------+
/*
Abrams Creek Campground allows RVs
*/
SELECT
name
FROM
camp_example
WHERE
is_rv_allowed = 1;
-- result
-- +-------------------------+
-- | name |
-- +-------------------------+
-- | Abrams Creek Campground |
-- +-------------------------+
/*
Adirondack Shelters does not allow RVs
*/
SELECT
name
FROM
camp_example
WHERE
is_rv_allowed = 0;
-- result
-- +---------------------+
-- | name |
-- +---------------------+
-- | Adirondack Shelters |
-- +---------------------+