如何从sql server将数据导入mongodb？
我在sql数据库中有以下列
的这些表州，城市，CityAreas
States Id Name Cities Id Name StatesId CitiArea Id Name CityId
我想要mongoDb中的数据。
{
State:"Orissa",
Cities:{
CitiName:"Phulbani",
CitYArea:{
"Phulbani","Phulbani2","Pokali","Madira"
}
}
}
是否有任何工具或我是否需要为此数据转换编写代码？
答案 0 :(得分：15)
有几种可能的方法可以通过使用适当的API选择您喜欢的语言编写代码来选择数据，转换然后将其插入MongoDB。
您也可以使用SQL，MongoDB查询语言和shell来完成。一种直接的方法是通过SQL选择平面数据，将其转储到CSV文件中，将其导入MongoDB并使用聚合框架将其转换为您想要的格式。
如果您足够幸运地使用支持数组的数据库或将行分组为单个列表类型的其他方法，那么您可以进行单个选择并将其转换为JSON或MongoDB插入语句。
对于这些示例，我假设您希望格式等同于每个城市的文档：
{
State:"Orissa",
City:{
Name:"Phulbani",
Area:[
"Phulbani","Phulbani2","Pokali","Madira"
]
}
}
RDBMS中的示例数据：
asya=# select * from states;
id | name
----+---------------
1 | California
2 | New York
3 | Massachusetts
(3 rows)
asya=# select * from cities;
id | name | states_id
----+---------------+-----------
1 | Los Angeles | 1
2 | San Francisco | 1
3 | San Diego | 1
4 | New York | 2
5 | Brooklyn | 2
6 | Buffalo | 2
7 | Boston | 3
(7 rows)
asya=# select * from cityarea;
id | name | city_id
----+--------------------+---------
1 | Beacon Hill | 7
2 | Backbay | 7
3 | Brookline | 7
4 | Park Slope | 5
5 | Little Italy | 4
6 | SOHO | 4
7 | Harlem | 4
8 | West Village | 4
9 | SoMa | 2
10 | South Beach | 2
11 | Haight Ashbury | 2
12 | Cole Valley | 2
13 | Bunker Hill | 1
14 | Skid Row | 1
15 | Fashion District | 1
16 | Financial District | 1
(16 rows)
数组的简单方法：
SELECT 'db.cities.insert({ state:"' || states.name || '", city: { name: "' || cities.name || '", areas : [ ' || array_to_string(array_agg('"' || cityarea.name || '"'),',') || ']}});'
FROM states JOIN cities ON (states.id=cities.states_id) LEFT OUTER JOIN cityarea ON (cities.id=cityarea.city_id) GROUP BY states.name, cities.name;
为您提供可以直接进入MongoDB shell的输出：
db.cities.insert({ state:"California", city: { name: "Los Angeles", areas : [ "Financial District","Fashion District","Skid Row","Bunker Hill"]}});
db.cities.insert({ state:"California", city: { name: "San Diego", areas : [ ]}});
db.cities.insert({ state:"California", city: { name: "San Francisco", areas : [ "Haight Ashbury","South Beach","SoMa","Cole Valley"]}});
db.cities.insert({ state:"Massachusetts", city: { name: "Boston", areas : [ "Beacon Hill","Brookline","Backbay"]}});
db.cities.insert({ state:"New York", city: { name: "Brooklyn", areas : [ "Park Slope"]}});
db.cities.insert({ state:"New York", city: { name: "Buffalo", areas : [ ]}});
db.cities.insert({ state:"New York", city: { name: "New York", areas : [ "Little Italy","West Village","Harlem","SOHO"]}});
如果您不支持数组或列表类型，则更长的方法是选择联接数据：
asya=# SELECT states.name as state, cities.name as city, cityarea.name as area
FROM states JOIN cities ON (states.id=cities.states_id)
LEFT OUTER JOIN cityarea ON (cities.id=cityarea.city_id);
state | city | area
---------------+---------------+--------------------
California | Los Angeles | Financial District
California | Los Angeles | Fashion District
California | Los Angeles | Skid Row
California | Los Angeles | Bunker Hill
California | San Francisco | Cole Valley
California | San Francisco | Haight Ashbury
California | San Francisco | South Beach
California | San Francisco | SoMa
California | San Diego |
New York | New York | West Village
New York | New York | Harlem
New York | New York | SOHO
New York | New York | Little Italy
New York | Brooklyn | Park Slope
New York | Buffalo |
Massachusetts | Boston | Brookline
Massachusetts | Boston | Backbay
Massachusetts | Boston | Beacon Hill
(18 rows)
我在cityarea上使用了一个左外连接，因为在我的示例数据中，我有一个没有列出任何区域的城市但是我想要获得所有州，城市对，即使没有列出的区域。
您可以通过交互方式或通过命令行（使用适当的RDBMS语法）将其转储出来。我将以交互方式进行：
asya=# \a
Output format is unaligned.
asya=# \f
Field separator is "|".
asya=# \f ,
Field separator is ",".
asya=# \t
Showing only tuples.
asya=# \o dump.txt
asya=# SELECT states.name as state, cities.name as city, cityarea.name as area
FROM states JOIN cities ON (states.id=cities.states_id)
LEFT OUTER JOIN cityarea ON (cities.id=cityarea.city_id);
asya=# \q
我现在有一个以逗号分隔的文件，其中州，城市和区域为三个字段。我可以通过mongoimport实用程序
asya$ mongoimport -d sample -c tmpcities --type csv --fields state,city,area < dump.txt
connected to: 127.0.0.1
2014-08-05T07:41:36.744-0700 check 9 18
2014-08-05T07:41:36.744-0700 imported 18 objects
现在转换为我想要的格式，我使用聚合：
mongo sample
MongoDB shell version: 2.6.4
connecting to: sample1
> db.tmpcities.aggregate(
{$group:{_id:"$city", state:{$first:"$state"}, areas:{$push:"$area"}}},
{$project:{state:1,_id:0,city:{name:"$_id", areas:"$areas"}}},
{$out:'cities'})
> db.cities.find({},{_id:0})
{ "_id" : "Boston", "state" : "Massachusetts", "areas" : [ "Brookline", "Backbay", "Beacon Hill" ] }
{ "_id" : "New York", "state" : "New York", "areas" : [ "West Village", "Harlem", "SOHO", "Little Italy" ] }
{ "_id" : "Buffalo", "state" : "New York", "areas" : [ "" ] }
{ "_id" : "Brooklyn", "state" : "New York", "areas" : [ "Park Slope" ] }
{ "_id" : "San Diego", "state" : "California", "areas" : [ "" ] }
{ "_id" : "San Francisco", "state" : "California", "areas" : [ "Cole Valley", "Haight Ashbury", "South Beach", "SoMa" ] }
{ "_id" : "Los Angeles", "state" : "California", "areas" : [ "Financial District", "Fashion District", "Skid Row", "Bunker Hill" ] }
答案 1 :(得分：3)
试试Mongify。它在MongoDB中迁移数据时会处理SQL中存在的所有外键和引用完整性约束 根据其文件：
Mongify可帮助您移动数据，而无需担心ID或外部ID。它允许您将数据嵌入到文档中，包括多态关联。
希望它有所帮助。