回答編集履歴
2
修正
test
CHANGED
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@@ -22,7 +22,7 @@
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22
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(5,'タイトルA-1-1',4),
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-
(6,'タイトルA-1-2',
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+
(6,'タイトルA-1-2',4),
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(7,'タイトルA-2',1);
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1
参考
test
CHANGED
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@@ -1,3 +1,119 @@
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1
1
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いまのデータ管理方法では何をやっても無駄でしょう
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2
2
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3
3
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ちゃんとやるなら入れ子集合モデルという方式をつかいます。
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4
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+
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5
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6
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7
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# sample
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8
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9
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```SQL
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10
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+
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11
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create table tbl (id int primary key,name varchar(30),parent_id int,level int,l int,r int);
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12
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insert into tbl(id,name,parent_id) values
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14
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(1,'タイトルA',null),
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16
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(2,'タイトルB',null),
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(3,'タイトルC',null),
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21
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(4,'タイトルA-1',1),
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22
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23
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+
(5,'タイトルA-1-1',4),
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24
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25
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+
(6,'タイトルA-1-2',5),
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26
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27
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+
(7,'タイトルA-2',1);
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28
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29
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```
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30
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# procedure
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33
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```SQL
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DROP PROCEDURE IF EXISTS SET_LR;
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DELIMITER //
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CREATE PROCEDURE SET_LR()
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40
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BEGIN
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DECLARE a INT DEFAULT 0;
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DECLARE done INT DEFAULT 0;
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DECLARE CUR CURSOR FOR
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48
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SELECT id FROM tbl WHERE level=0 ORDER BY parent_id ASC,id DESC;
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DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;
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UPDATE tbl SET level=0,l=0,r=0;
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55
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56
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UPDATE tbl SET level=1,l=(SELECT @a:=@a+1 FROM (SELECT @a:=0) AS sub),r=@a:=@a+1
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58
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59
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WHERE parent_id IS NULL
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60
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61
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ORDER BY id;
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62
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63
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64
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65
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OPEN CUR;
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66
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67
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REPEAT
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68
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69
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FETCH CUR INTO a;
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70
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71
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IF NOT done THEN
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72
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SET @id=a;
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74
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75
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SET @sql='UPDATE tbl as a1,tbl as a2,tbl as a3 SET a1.l=a2.l+1,a1.r=a2.l+2,a1.level=a2.level+1,a2.r=a2.r+2,a3.r=a3.r+2 WHERE a1.parent_id=a2.id AND a2.l<a3.r AND a1.id=?';
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76
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77
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78
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79
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PREPARE stmt from @sql;
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80
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81
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EXECUTE stmt USING @id;
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82
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83
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SET @sql='UPDATE tbl as a1,tbl as a2,tbl as a3 SET a3.l=a3.l+2 WHERE a1.parent_id=a2.id AND a2.l<a3.l and a3.id!=a1.id AND a1.id=?';
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84
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+
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85
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+
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86
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+
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87
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PREPARE stmt from @sql;
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88
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+
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89
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EXECUTE stmt USING @id;
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90
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+
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91
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END IF;
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92
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93
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UNTIL done END REPEAT;
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94
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95
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CLOSE CUR;
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96
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97
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END
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98
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99
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//
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100
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101
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DELIMITER ;
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102
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103
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```
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104
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+
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105
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# 実行
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106
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+
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107
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```SQL
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108
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+
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109
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call set_lr;
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110
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+
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111
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+
```
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112
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+
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113
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# 表示
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114
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115
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```SQL
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116
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+
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117
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select * from tbl order by l;
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118
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+
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119
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+
```
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