Question

我有一些SQL Server对于存储的数据是相同的，我希望能够在它们之间进行更改，如果我添加更多，我想轻松添加它们与Windows窗体。

我首先完成了一个数据库，这是添加到App.config文件的连接字符串。出于安全原因，我更改了用户名和密码

data.label

有没有一种简单的方法来改变我应该从哪里获取数据？我正在考虑使用一个组合框，我可以选择从哪个SQL Server获取数据。如果我手动更改连接字符串，它的工作原理。但我怎么用代码呢？

Answer 1

您可以使用类EntityConnectionStringBuilder来构建连接字符串。请参阅此处https://msdn.microsoft.com/en-us/library/orm-9780596520281-01-16.aspx和Programmatic Connection Strings in Entity Framework 6

// Specify the provider name, server and database.
        string providerName = "System.Data.SqlClient";
        string serverName = ".";
        string databaseName = "AdventureWorks";

        // Initialize the connection string builder for the
        // underlying provider.
        SqlConnectionStringBuilder sqlBuilder =
            new SqlConnectionStringBuilder();

        // Set the properties for the data source.
        sqlBuilder.DataSource = serverName;
        sqlBuilder.InitialCatalog = databaseName;
        sqlBuilder.IntegratedSecurity = true;

        // Build the SqlConnection connection string.
        string providerString = sqlBuilder.ToString();

        // Initialize the EntityConnectionStringBuilder.
        EntityConnectionStringBuilder entityBuilder =
            new EntityConnectionStringBuilder();

        //Set the provider name.
        entityBuilder.Provider = providerName;

        // Set the provider-specific connection string.
        entityBuilder.ProviderConnectionString = providerString;

        // Set the Metadata location.
        entityBuilder.Metadata = @"res://*/AdventureWorksModel.csdl|
                        res://*/AdventureWorksModel.ssdl|
                        res://*/AdventureWorksModel.msl";
        Console.WriteLine(entityBuilder.ToString());

        using (EntityConnection conn =
            new EntityConnection(entityBuilder.ToString()))
        {
            conn.Open();
            Console.WriteLine("Just testing the connection.");
            conn.Close();
        }

Answer 2

我做了什么让它发挥作用。在上下文文件中，我更改了

public MigrateDBFaktura3Entities ()
            : base("name=MigrateDBFaktura3Entities")
        {

        }

到

public MigrateDBFaktura3Entities (string connectionString)
            : base(connectionString)
        {

        }

然后我做了一个HelperClass

class ConnectionHelper
    {
        public static string CreateConnectionString(LocationModel LM, string metaData)
        {
            const string appName = "EntityFramework";
            const string providerName = "System.Data.SqlClient";

            SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder();
            sqlBuilder.DataSource = LM.datasource;
            sqlBuilder.InitialCatalog = LM.catalog;
            sqlBuilder.UserID = LM.Username;
            sqlBuilder.Password = LM.Password;
            sqlBuilder.MultipleActiveResultSets = true;
            sqlBuilder.PersistSecurityInfo = true;
            sqlBuilder.ApplicationName = appName;


EntityConnectionStringBuilder efBuilder = new EntityConnectionStringBuilder();
        efBuilder.Metadata = metaData;
        efBuilder.Provider = providerName;
        efBuilder.ProviderConnectionString = sqlBuilder.ConnectionString;
        var t = efBuilder.ConnectionString;
        return efBuilder.ConnectionString;
    }

    public static FastecData CreateConnection(LocationModel locationmodel, string metaData = "res://*/DB.ServerData.csdl|res://*/DB.ServerData.ssdl|res://*/DB.ServerData.msl")
    {
        return new FastecData(ConnectionHelper.CreateConnectionString(locationmodel, metaData));
    }
}

LocationModel是数据库，它纯粹包含我将连接到的不同服务器的数据以从中获取数据。

然后，当我需要连接到它时，我只需要

MigrateDBFaktura3Entities db = ConnectionHelper.CreateConnection(CurrentLocation)

其中CurrentLocation是LocationModel

使用C＃Form动态连接到多个SQL Server？

2 个答案: