Question

未将对象引用设置到对象的实例

这个应该怎么改？
protected void Page_Load(object sender, EventArgs e)
{string connstr =ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();
SqlConnection objCon = new SqlConnection(connstr);
objCon.Open();
string strSql = "select quanxian from [user] where name='" + Session["name"] + "'";
SqlCommand objCmd = new SqlCommand(strSql, objCon);
string quanxian= (string)objCmd.ExecuteScalar().ToString();

}

Answer 1

ExecuteScalar()执行得到的内容有问题
一般都得加个判断是否为空
比如：
try
{
SqlCommand cmd = new SqlCommand(safeSql, Connection);
Object o = cmd.ExecuteScalar();
if ((o != null) && (o != DBNull.Value))
{ string quanxian = o.ToString(); }
}
catch (Exception ex)
{

throw;
}

Answer 2

objCmd.ExecuteScalar()的返回值可能为空，代码需要处理这样的情况