后台连接数据库的方法

1.直接写数据库连接字符串

string constr = "server=.;database=myschool;integrated security=SSPI";
//string constr = "server=.;database=myschool;uid=sa;pwd=sa";
//string constr = "data source=.;initial catalog=myschool;user id=sa;pwd=sa";
SqlConnection con = new SqlConnection(constr);
// con.ConnectionString = constr;
string sql = "select count(*) from grade";
SqlCommand com = new SqlCommand(sql,con);
try
{
      con.Open();
      MessageBox.Show("成功连接数据库");
      int x = (int)com.ExecuteScalar();
      MessageBox.Show(string.Format("成功读取{0},条记录", x));
}
catch (Exception)
{

      throw;
}
finally
{
      con.Close();
      MessageBox.Show("成功关闭数据库连接", "提示信息", MessageBoxButtons.YesNoCancel);
}

2.web.config配置

<!--webconfig中配置：-->
<?xml version="1.0"?>
<configuration>
<connectionStrings>
<add name="myschool" connectionString="Server=localhost;Integrated Security=True;Database=myschool;Persist Security Info=True" providerName="System.Data.SqlClient" />
</connectionStrings>
<system.web>
<pages styleSheetTheme="Default"/>
</system.web>
</configuration>

C#后台处理程序

string connectionString =ConfigurationManager.ConnectionStrings["myschool"].ConnectionString;

<!--webconfig中配置：-->  
 <appSettings>  
  <add key="ConnectionString" value="server=服务器地址;database=数据库名称;uid=服务器地址;pwd=密码;/>  
  
 </appSettings>

private string strCon = ConfigurationManager.AppSettings["ConnectionString"];