回答編集履歴
4
推敲
test
CHANGED
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@@ -99,5 +99,3 @@
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|
99
99
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left join camera ON base.observed= camera.recorded and base.id = camera.id
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100
100
|
|
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101
101
|
```
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102
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-
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103
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-
速度的にはhatenaさんの回答の記述の方が早いと思われます。
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3
追記
test
CHANGED
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@@ -65,3 +65,39 @@
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65
65
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left join mybook4 ON base.id = mybook4.id
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66
66
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67
67
|
```
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68
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+
|
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69
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+
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|
70
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+
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71
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+
質問が変更されたので追記
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72
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+
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73
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+
--
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74
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+
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75
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+
```SQL
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|
76
|
+
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77
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+
SELECT base.id, meter1.observed, meter2.observed, camera.recorded
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78
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+
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|
79
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+
FROM (
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|
80
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+
|
|
81
|
+
select observed, id from (
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|
82
|
+
|
|
83
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+
select observed, id from meter1
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|
84
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+
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|
85
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+
union all select observed, id from meter2
|
|
86
|
+
|
|
87
|
+
union all select recorded, id from camera
|
|
88
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+
|
|
89
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+
) step1
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|
90
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+
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91
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+
group by observed, id
|
|
92
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+
|
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93
|
+
) base
|
|
94
|
+
|
|
95
|
+
left join meter1 ON base.observed= meter1.observed and base.id = meter1.id
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|
96
|
+
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|
97
|
+
left join meter2 ON base.observed= meter2.observed and base.id = meter2.id
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|
98
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+
|
|
99
|
+
left join camera ON base.observed= camera.recorded and base.id = camera.id
|
|
100
|
+
|
|
101
|
+
```
|
|
102
|
+
|
|
103
|
+
速度的にはhatenaさんの回答の記述の方が早いと思われます。
|
2
追記
test
CHANGED
|
@@ -27,3 +27,41 @@
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|
27
27
|
left join mybook4 ON base.id = mybook4.id
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|
28
28
|
|
|
29
29
|
```
|
|
30
|
+
|
|
31
|
+
|
|
32
|
+
|
|
33
|
+
以下は冗長になりますが、unionマージでない分高速であるかもしれません。
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34
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+
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35
|
+
特にidに対してindexが設定されているようならさらに。
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|
36
|
+
|
|
37
|
+
```SQL
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|
38
|
+
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|
39
|
+
SELECT base.id, mybook.name, mybook2.name, mybook3.name, mybook4.name
|
|
40
|
+
|
|
41
|
+
FROM (
|
|
42
|
+
|
|
43
|
+
select id from (
|
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44
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+
|
|
45
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+
select id from mybook
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46
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+
|
|
47
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+
union all select id from mybook2
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|
48
|
+
|
|
49
|
+
union all select id from mybook3
|
|
50
|
+
|
|
51
|
+
union all select id from mybook4
|
|
52
|
+
|
|
53
|
+
) step1
|
|
54
|
+
|
|
55
|
+
group by id
|
|
56
|
+
|
|
57
|
+
) base
|
|
58
|
+
|
|
59
|
+
left join mybook ON base.id = mybook.id
|
|
60
|
+
|
|
61
|
+
left join mybook2 ON base.id = mybook2.id
|
|
62
|
+
|
|
63
|
+
left join mybook3 ON base.id = mybook3.id
|
|
64
|
+
|
|
65
|
+
left join mybook4 ON base.id = mybook4.id
|
|
66
|
+
|
|
67
|
+
```
|
1
推敲
test
CHANGED
|
@@ -1,4 +1,4 @@
|
|
|
1
|
-
idを集約するのにfull outerでは無理があります。
|
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1
|
+
idを集約するのに、３つ以上のテーブルでfull outerで行うには無理があります。
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2
2
|
|
|
3
3
|
一旦全てのIDのリストを取得し、それを元に結合します。
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4
4
|
|