sql join 연습장 - http://bit.ly/join-exec

	A	B	C	D	E	F	G	H	I	J	K	L	M	N
1	topic								comment
2	tid	title	description	name	city	job_title	job_description		cid	description	name	city	job_title	job_description
3	1	HTML	HTML is …	egoing	jeju	developer	developer is …		1	lorem ...	egoing	jeju	developer	developer is …
4	2	CSS	CSS is …	leezche	jeju	designer	designer is …
5	3	Database	Database is ..	egoing	jeju	developer	developer is …
6
7	Every table in the database needs to have a single theme
8
9	topic					author					profile
10	tid	title	description	author_id		id	name	city	profile_id		id	job_title	job_description
11	1	HTML	HTML is …	1		1	egoing	seoul	1		1	developer	developer is …
12	2	CSS	CSS is …	2		2	leezche	jeju	2		2	designer	designer is …
13	3	Database	Database is ..	1
14
15	author					profile				topic
16	id	name	city	profile_id		id	job_title	job_description		tid	title	description	author_id
17	1	egoing	cheoung-ju	1		1	developer	developer is …		1	HTML	HTML is …	1
18	2	leezche	jeju	2		2	designer	designer is …		2	CSS	CSS is …	2
19	3	duru	seoul	1						3	Database	Database is ..	1
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
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100