質問編集履歴
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@@ -9,7 +9,6 @@
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- グループでもメッセージを送れる
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- グループにはユーザーを追加、削除できる
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- グループ名を変えられる
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- 全メッセージの中から文字queryで検索可能
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=============
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```lang-sql
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@@ -52,21 +51,21 @@
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foreign key (id) references users(id)
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);
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insert into groups (group_id, group_name) values (1,'school');
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insert into groups (group_id, group_name,id) values (1,'school',1,);
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insert into groups (group_id, group_name,id) values (2,'school',3,);
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insert into groups (group_id, group_name) values (
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insert into groups (group_id, group_name,id) values (3,'bestfried',2,);
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insert into groups (group_id, group_name) values (
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insert into groups (group_id, group_name,id) values (4,'teamA',2,);
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create table schools (
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school_id int primary key,
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school_message_content text,
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id int,
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foreign key (id) references users(id)
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foreign key (id) references users(id)
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group_id int,
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foreign key (group_id) references groups (group_id)
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);
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insert into schools (school_id,
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insert into schools (school_id, school_message_content) values (1, 'aaa');
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insert into schools (school_id,
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insert into schools (school_id, school_message_content) values (2, 'bbb');
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insert into schools (school_id,
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insert into schools (school_id, school_message_content) values (3, 'ccc');
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create table messages(
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message_id int,
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@@ -82,6 +81,7 @@
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insert into messages (message_id, message_content) values (1, 'hoge?');
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insert into messages (message_id, message_content) values (2, 'hoge!!!');
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insert into messages (message_id, message_content) values (3, 'hoge');
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insert into messages (message_id, message_content) values (4, 'honcon');
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```
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以下の命令を実行するMysql文を出力しました。
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@@ -93,16 +93,41 @@
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=============
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```lang-sql
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(1)select messages.message_content from users
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inner join messages on users.id = messages.message_id
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inner join groups on users.id = groups.group_id
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inner join schools on schools.school_id = schools.school_id
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where groups.group_id = 1;
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(2)不明
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(3)不明
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(
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(1)select messages.message_content from messages
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inner join users on messages.message_id = users.id
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inner join friends on messages.message_id = friends.friend_id
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where users.id = 1 and users.id = 2;
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+
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(2)select users.name from users
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inner join groups on users.id = groups.id
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where group_name = 'school';
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(3)select schools.school_message_content from schools;
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where messages.message_content
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(4)where messages.message_content like '%hoge%';
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```
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自分で把握している疑問点は一つあります。
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上記のsql文で、グループラインのテーブル(shools)のメッセージ履歴を書いたのですが、
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```lang-sql
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(3)select schools.school_message_content from schools;
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```
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下記のように、グループラインごとにテーブルをひとつずつ作成していたら膨大なテーブル数に成ってしまいますよね。
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+
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```sql
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create table schools (
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school_id int primary key,
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school_message_content text,
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id int,
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foreign key (id) references users(id)
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);
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insert into schools (school_id, school_message_content) values (1, 'aaa');
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insert into schools (school_id, school_message_content) values (2, 'bbb');
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insert into schools (school_id, school_message_content) values (3, 'ccc');
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```
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グループテーブルの中に、グループラインそれぞれの履歴を格納したいのですが、どのように記入してあげればいいのかが分かりません。
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