在控制台应用程序中定义连接字符串

Question

我正在尝试create a connection，但它始终采用null。 下面我提的一个方式，我怎么做：

的Program.cs：

SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["CreateConnection"].ConnectionString); 

的App.config：

<configuration> 

    <connectionStrings> 
    <add name="CreateConnection" connectionString="data source=MyDatabase;initial catalog=TestDatabase;integrated security=True;MultipleActiveResultSets=True;user id=ABC;password=Admin@123;App=EntityFramework;" providerName="System.Data.EntityClient" /> 
    </connectionStrings> 

</configuration> 

Answer 1

我用下面的方式。检查这有助于用于MySQL的

在App.config文件

<appSettings> 
    <add key="DBConnectionString" 
    value="server=localhost;userid=root;database=databasename"/> 
    </appSettings> 

在Program.cs的

public static string m_strMySQLConnectionString; 
static MySqlConnection m_mySqlConnection; 

static void Main(string[] args) 
{ 
    m_strMySQLConnectionString = ConfigurationManager.AppSettings["DBConnectionString"].ToString(); 
    m_mySqlConnection = null; 
} 

在DB辅助函数

public string GetValueFromDB(string strQuery) 
    { 
     string strData = ""; 

     try 
     { 
      if (m_mySqlConnection == null) 
       OpenDatabase(); 

      if (string.IsNullOrEmpty(strQuery) == true) 
       return string.Empty; 

      MySqlCommand cmd = new MySqlCommand(strQuery, m_mySqlConnection); 
      object objValue = cmd.ExecuteScalar(); 
      if (objValue == null) 
      { 
       cmd.Dispose(); 
       return string.Empty; 
      } 
      else 
      { 
       strData = (string)cmd.ExecuteScalar(); 
       cmd.Dispose(); 
      } 

      if (strData == null) 
       return string.Empty; 
      else 
       return strData; 
     } 
     catch (MySqlException ex) 
     { 
      LogException(ex); 
      return string.Empty; 
     } 
     catch (Exception ex) 
     { 
      LogException(ex); 
      return string.Empty; 
     } 
     finally 
     { 
      CloseDatabase(); 
     } 
    }