mysql到mongodb数据库及查询转换

MySQL数据库中定义的以下结构

我有一个学位表
包含两列：学位id、学位名称
2.分行另一张表
分支机构id、分支机构名称、学位id
3.主题表
学科id、学科名称、学科代码、学位id、学期
4.教学大纲

---

现在，我可以使用mysql轻松获取分词学位、分支、学期的教学大纲，但我是mongo db的新手，请帮助在

MongoDb

中，您必须将概念更一般化，并包含其中的所有关系

您的数据库

Mysql

，在

mongodb

上看起来像这样：

     degree{
            _id : ...,
            name : ...,
            branches :[ {
                         _id: ...
                         name: ....,
                         syllabus : [ {
                                       _id: ...,
                                       name: ....,
                                       sort_note: ....
                                       attachment:...
                                       semetster,... 
                                      } , ..   ],...{
                       } ],
             subjects: [ {
                          _id: ..,
                          name: ....,
                          code: .....,
                          semester: ....
                       }, ...]
             }

如果id_分支和id_度是唯一的，就像containt是对象一样，那么其他的是数组

---

关于

我查看了您的SQL数据模型，但对我来说有些不太清楚。 似乎你把学位加入了每一个集合（分支/学科/教学大纲）

我猜你最终会在最高级别的学位id（分支id/学科id）上查询你的教学大纲

select * from syllabus where degree_id = ?

或

这意味着你不需要像这样通过在分支或学科上设置的学位id来搜索教学大纲

select s.* from syllabus s
join branch b on b.branch_id = s.branch_id
join subject su on su.subject_id = s.subject_id
where b.degree_id = ? // or su.degree_id = ?

[
   {
   _id : ObjectId('syllabus_id_1'), //_id or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : {
      degree_id : ObjectId('degree_id_1'),
      degree_name : 'degree1'
   },
   branch : {
      branch_id : ObjectId('branch_id_1'),
      branch_name : 'branch1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   },
   subject : {
      subject_id : ObjectId('subject_id_1'),
      subject_name : 'subject1',
      subject_code : 'code',
      semester : 'semester1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   }
   }
]

syllabus.find({'degree.degree_id':ObjectId('degree_id_1'), 'degree.degree_name':'degree1'})

[
   {
   _id : ObjectId('syllabus_id_1'), //or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : ObjectId('degree_id_1'),
   branch : ObjectId('branch_id_1'),
   subject : ObjectId('subject_id_1'),
   }
]

syllabus.find({degree:ObjectId('degree_id_1')})

所以，假设您确实通过为教学大纲记录设置的学位id来搜索教学大纲集合。 这使得在MongoDB中更容易获得相同的结果

将当前SQL模型转换为MongoDB模型的最简单方法是使用4个集合而不是4个表

学位

{
   degree_id : ...
   degree_name : ...
}

分支机构

{
   branch_id : ...
   branch_name : ...
   degree : {
      degree_id : ...
      degree_name : ...
   }
}

科目也是如此，教学大纲中嵌入学位、分支和科目文档的方式最终也是如此。 MongoDB不需要固定关系或外键，也没有关系数据库中的连接。因此，要么嵌入其他集合，要么通过_id字段添加对文档的引用（就像SQL一样），这取决于最终的查询结果

嵌入教学大纲集合中的其他集合如下所示

select s.* from syllabus s
join branch b on b.branch_id = s.branch_id
join subject su on su.subject_id = s.subject_id
where b.degree_id = ? // or su.degree_id = ?

[
   {
   _id : ObjectId('syllabus_id_1'), //_id or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : {
      degree_id : ObjectId('degree_id_1'),
      degree_name : 'degree1'
   },
   branch : {
      branch_id : ObjectId('branch_id_1'),
      branch_name : 'branch1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   },
   subject : {
      subject_id : ObjectId('subject_id_1'),
      subject_name : 'subject1',
      subject_code : 'code',
      semester : 'semester1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   }
   }
]

syllabus.find({'degree.degree_id':ObjectId('degree_id_1'), 'degree.degree_name':'degree1'})

[
   {
   _id : ObjectId('syllabus_id_1'), //or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : ObjectId('degree_id_1'),
   branch : ObjectId('branch_id_1'),
   subject : ObjectId('subject_id_1'),
   }
]

syllabus.find({degree:ObjectId('degree_id_1')})

这样你就可以像这样查询你的教学大纲了

select s.* from syllabus s
join branch b on b.branch_id = s.branch_id
join subject su on su.subject_id = s.subject_id
where b.degree_id = ? // or su.degree_id = ?

[
   {
   _id : ObjectId('syllabus_id_1'), //_id or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : {
      degree_id : ObjectId('degree_id_1'),
      degree_name : 'degree1'
   },
   branch : {
      branch_id : ObjectId('branch_id_1'),
      branch_name : 'branch1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   },
   subject : {
      subject_id : ObjectId('subject_id_1'),
      subject_name : 'subject1',
      subject_code : 'code',
      semester : 'semester1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   }
   }
]

syllabus.find({'degree.degree_id':ObjectId('degree_id_1'), 'degree.degree_name':'degree1'})

[
   {
   _id : ObjectId('syllabus_id_1'), //or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : ObjectId('degree_id_1'),
   branch : ObjectId('branch_id_1'),
   subject : ObjectId('subject_id_1'),
   }
]

syllabus.find({degree:ObjectId('degree_id_1')})

或

或者您只使用_id字段链接到其他集合，在这种情况下，您的教学大纲文档如下所示

select s.* from syllabus s
join branch b on b.branch_id = s.branch_id
join subject su on su.subject_id = s.subject_id
where b.degree_id = ? // or su.degree_id = ?

[
   {
   _id : ObjectId('syllabus_id_1'), //_id or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : {
      degree_id : ObjectId('degree_id_1'),
      degree_name : 'degree1'
   },
   branch : {
      branch_id : ObjectId('branch_id_1'),
      branch_name : 'branch1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   },
   subject : {
      subject_id : ObjectId('subject_id_1'),
      subject_name : 'subject1',
      subject_code : 'code',
      semester : 'semester1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   }
   }
]

syllabus.find({'degree.degree_id':ObjectId('degree_id_1'), 'degree.degree_name':'degree1'})

[
   {
   _id : ObjectId('syllabus_id_1'), //or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : ObjectId('degree_id_1'),
   branch : ObjectId('branch_id_1'),
   subject : ObjectId('subject_id_1'),
   }
]

syllabus.find({degree:ObjectId('degree_id_1')})

您只能通过以下id字段查询教学大纲

select s.* from syllabus s
join branch b on b.branch_id = s.branch_id
join subject su on su.subject_id = s.subject_id
where b.degree_id = ? // or su.degree_id = ?

[
   {
   _id : ObjectId('syllabus_id_1'), //_id or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : {
      degree_id : ObjectId('degree_id_1'),
      degree_name : 'degree1'
   },
   branch : {
      branch_id : ObjectId('branch_id_1'),
      branch_name : 'branch1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   },
   subject : {
      subject_id : ObjectId('subject_id_1'),
      subject_name : 'subject1',
      subject_code : 'code',
      semester : 'semester1',
      degree : {
         degree_id  : ObjectId('degree_id_1'),
         degree_name : 'degree1'
      }
   }
   }
]

syllabus.find({'degree.degree_id':ObjectId('degree_id_1'), 'degree.degree_name':'degree1'})

[
   {
   _id : ObjectId('syllabus_id_1'), //or syllabus_id but MongoDB adds an _id field automatically,
   syllabus_name : 'syllabus1',
   sort_note : 'a note',
   attachment : 'my attachment',
   semester : 'semester1',
   degree : ObjectId('degree_id_1'),
   branch : ObjectId('branch_id_1'),
   subject : ObjectId('subject_id_1'),
   }
]

syllabus.find({degree:ObjectId('degree_id_1')})

或

我希望您理解这个概念，并决定哪种方法更适合您的应用程序。这完全取决于您的教学大纲文档在查询结果中的外观

在我的应用程序中，我总是先考虑查询，然后对文档建模

您应该始终记住，您没有连接，有一些插件可以为您提供某种连接和预定义的模型布局，如Mongoose。但在我看来，这与MongoDB完全背道而驰。尝试以MongoDB方式对数据建模：-）

---

如果有不清楚的地方，请告诉我。

如果您能描述实体之间的一对一和一对多关系，那就更好了。例如，我猜教学大纲和学科之间有一对一的关系，一个分支会有许多学科。但我不确定学位和分支的关系。一个分支机构可以拥有多个学位，或者反之亦然？问题是从2013年开始，您仍然在使用m8 lel