ADO.NET标准写法

/// <summary>
/// 数据库连接对象
/// </summary>
private static SqlConnection conn = new SqlConnection("server=.//accp;database=stuDB;uid=sa;pwd=ok;");
/// <summary>
/// 非查询操作
/// </summary>
/// <param name="cmd">SqlCommand对象</param>
/// <returns>影响行数</returns>
public static int ExecuteQuery(SqlCommand cmd)
{
cmd.Connection = conn;
try
{
conn.Open();
return cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
throw ex;
}
finally
{

if (conn != null)
{
//关闭数据库连接
conn.Close();
}

}
}
/// <summary>
/// 查询单个数据的方法
/// </summary>
/// <param name="cmd">SqlCommand对象</param>
/// <returns>object类型数据</returns>
public static object ExecuteScalar(SqlCommand cmd)
{
cmd.Connection = conn;
try
{
conn.Open();
return cmd.ExecuteScalar();
}
catch (Exception ex)
{
throw ex;
}
finally
{

if (conn != null)
{
//关闭数据库连接
conn.Close();
}

}
}

 

使用using方式：

//编写数据库连接串
string connStr = "Data source=.;Initial Catalog=test;User ID=sa;Password=pwdpwd";
//创建SqlConnection的实例
try
{
    using(SqlConnection conn=new SqlConnection(connStr))
    {
        //打开数据库连接
        conn.Open();
        MessageBox.Show("数据库连接成功！");
    }
}
catch(Exception ex)
{
    MessageBox.Show("数据库连接失败！" + ex.Message);
}