回答編集履歴
1
sample
test
CHANGED
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@@ -3,3 +3,59 @@
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3
3
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ユニークな入力順のIDが振られる（最大値の次のデータ）
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4
4
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5
5
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程度のものだと思って下さい
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6
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+
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7
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8
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9
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# sample
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10
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+
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11
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ねんのためサンプル付けときます
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12
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13
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14
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15
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```SQL
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16
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17
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create table renzoku(ren int not null primary key auto_increment,aa varchar(10));
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18
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19
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insert into renzoku values(3,'aaa'),(4,'bbb'),(10,'ccc');
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20
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21
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insert into renzoku(aa) values('ddd');
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22
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23
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select * from renzoku;
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24
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25
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```
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26
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27
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2行目でauto_incrementの最大値が10となったのでdddのrenは11
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28
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29
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30
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31
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※連番を振り直して、新たなデータを投入、でもrenは12から
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32
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33
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```SQL
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34
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35
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update renzoku set ren=(select @a:=@a+1 from (select @a:=0) as dummy) order by ren;
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36
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37
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insert into renzoku(aa) values('eee');
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38
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39
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select * from renzoku;
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40
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41
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```
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42
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43
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再度連番を振り直し、auto_incrementを初期化した上で、データ投入
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44
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45
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```SQL
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46
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47
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update renzoku set ren=(select @a:=@a+1 from (select @a:=0) as dummy) order by ren;
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48
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49
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alter table renzoku auto_increment=1;
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50
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51
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insert into renzoku(aa) values('fff'),('ggg');
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52
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53
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select * from renzoku;
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54
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55
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56
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57
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```
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58
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59
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60
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61
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