multiple-databases | 易学教程

How to Merge Multiple Database files in SQLite?

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问题 I have multiple database files which exist in multiple locations with exactly similar structure. I understand the attach function can be used to connect multiple files to one database connection, however, this treats them as seperate databases. I want to do something like: SELECT uid, name FROM ALL_DATABASES.Users; Also, SELECT uid, name FROM DB1.Users UNION SELECT uid, name FROM DB2.Users ; is NOT a valid answer because I have an arbitrary number of database files that I need to merge.

EF Code First Migration with Multiple Database / DbContext

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I have two database each with their own dbcontext. I've setup two migration configurations. I can add a migration for the first db ust fine ( Add-Migration DB1_InitialCreate -ConfigurationTypeName DB1Configuration ). When I try to create an initial migration with the second db using: Add-Migration DB2_InitialCreate -ConfigurationTypeName DB2Configuration , I get the following error: Unable to generate an explicit migration because the following explicit migrations are pending: [201205082215265_DB1_InitialCreate]. Apply the pending explicit migrations before attempting to generate a new

Django TestCase not using transactions on secondary database

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问题 I am using Django 1.3.1. I have two databases, some of my models live in one database, some in the other. Both databases are contrib.gis.db.backends.postgis databases. To my surprise, Django's TestCase isn't rolling back changes I made in the secondary database between tests. In the following code, myproject.models.WellOwner is a very simple model that basically only has a field "name". The router says that it should be in the secondary database. The assertion in the first test succeeds, the

multi-tenant database architecture [closed]

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问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . I am building a SAAS application and we are discussing about one database per client vs shared databases. I have read a lot, incluisve some topics here at SO but I have still many doubts. Our plataform should be highly customizable by each client. (they should be able to have custom tables and add custom fields

Connecting to two databases Mongoid

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I have two databases that I have to use in my application. I have the following in my mongoid.yml : development: # Configure available database sessions. (required) sessions: # Defines the default session. (required) default: # Defines the name of the default database that Mongoid can connect to. # (required). database: db_development username: myusername password: mypassword # Provides the hosts the default session can connect to. Must be an array # of host:port pairs. (required) hosts: - myserverip:27017 databases: secondary: database: db2_development username: myusername password:

How to create multiple database connections for different databases in java

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I have an application which uses four databases in different geographical locations. All the databases contains same tables and only the database name is different according to the location. I have to create some reports in my application which uses data from each database. What would be the proper way to create those database connection from a java application and is there a suitable design pattern for this task which I could use? As you have not tagged your question with any of this, hibernate , JPA , ORM , I assume you are dealing with plain JDBC. Having said that, I suggest you to have a

.NET migrations: Setup and migrate multiple databases at runtime

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问题 Brief introduction: I have this ASP.NET Webforms site with the particularity that it doesn't have only 1 database, it has many. Why? Because you can create new "instances" of the site on-the-fly. Every "instance" share the same codebase, but has its own database. These all databases have the same schema (structure) but of course different data. Don't ask 'why don't you put everything in one database and use InstanceId to know which is" because it's a business policy thing. The application

How to retrieve data from multiple Stata files?

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I have 53 Stata .dta files each of them is 150 - 200 Mb and contain identical set of variables, but for different years. It is not useful to combine or merge them due to their size . I need to retrieve some averaged values (percentages etc.) Therefore, I want to create a new Stata file New.dta and write a .do file that would run on that new Stata file in the following way: it should open each of those 53 Stata files, make certain calulations, and store the results in the new Stata file, New.dta. I am not sure how i can keep two Stata file open simultaneuosly, and how can i store the calculated

Is it possible to have multiple core data “databases” on one iOS app?

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I'm wanting to write a "management" game that utilizes Core data heavily. The game requires a pre-set, pre-defined dataset that cannot be changed by the user/system; it is used to seed the game with data and is meant to be read-only. The best example I can give is a football management game, but it could be anything. In some football management sims they give you scenarios and pre-set datasets. As the user proceeds through the game they can save/load their progress which is saved to the core data. In addition to this, the user can receive updates to the pre-defined data or can purchase

Spring + Hibernate + JPA + multiple databases

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I have a Spring + Hibernate + JPA app. The user, when logging in, can choose from a list of DB's to connect to (these are the requirements). All the DB's have the same schema, so the same entities and DAO's will be used. Right now I have one EntityManager (been working with one database for the moment) that is injected in the DAO like this: @PersistenceContext private EntityManager entityManager; Is there any way to have the DAO receive the entityManager automatically (managed by Spring) based on a parameter/property received from the service layer ? (The web layer sends a kind of context, and