About DbProviderFactory

有时间研究了一下.net framework的DbProviderFactory (ADO.NET)， namespace：System.Data.Common;

使用

DbProviderFactory factory = DbProviderFactories.GetFactory(providerName);

connection = factory.CreateConnection();

可以很方便的创建不同类型的数据连接

首先在config文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionStrings>
    <clear/>
    <add name="NorthwindSQL"
     providerName="System.Data.SqlClient"
     connectionString=
     "Data Source=.;Initial Catalog=Northwind;Integrated Security=true"/>
    <add name="NorthwindAccess"
     providerName="System.Data.OleDb"
     connectionString=
     "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\Northwind.mdb;"/>
    <add name="NorthwindMySql"
         connectionString=
         "Server=172.29.131.27;Port=3311;DataBase=comctl;Persist Security Info=False;User ID=root;Password=123456;Allow Zero Datetime=true;"
         providerName="MySql.Data.MySqlClient"/>
</connectionStrings>

<system.data>
    <DbProviderFactories>
      <add name="MySQL Data Provider"
           invariant="MySql.Data.MySqlClient"
           description=".Net Framework Data Provider for MySQL"
           type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=5.2.5.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>
    </DbProviderFactories>
</system.data>
</configuration>

如果本地已经安装mysql，则不需要注册此配置信息

public static DataTable GetCategories()
{
DataTable table = new DataTable();

            string connName = System.Configuration.ConfigurationManager.AppSettings["Connection"];
            string connectionString = ConfigurationManager.ConnectionStrings[connName].ConnectionString;
            string providerName = ConfigurationManager.ConnectionStrings[connName].ProviderName;

            // Create the DbProviderFactory and DbConnection.
            DbProviderFactory factory =
                DbProviderFactories.GetFactory(providerName);

DbConnection connection = factory.CreateConnection();
connection.ConnectionString = connectionString;

            using (connection)
            {
                // Define the query.
                string queryString =
                    "SELECT * FROM Categories";

                // Create the DbCommand.
                DbCommand command = factory.CreateCommand();
                command.CommandText = queryString;
                command.Connection = connection;

                // Create the DbDataAdapter.
                DbDataAdapter adapter = factory.CreateDataAdapter();
                adapter.SelectCommand = command;

// Fill the DataTable.

adapter.Fill(table);
}

return table;
}

// Retrieve the installed providers and factories.
DataTable table = DbProviderFactories.GetFactoryClasses();

得到本机所有providers

深入理解http://technet.microsoft.com/zh-cn/office/wda6c36e.aspx