Question

为什么 无法将类型“System.Data.SqlClient.SqlDataReader”隐式转换为

bntlogin.Text = "";
string u_id = textBox1.Text;
string u_pwd = textBox2.Text;
SqlConnection conn = new SqlConnection(@"Date Source=.;database=user");
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = "select * from user where u_id=@un";
cmd.Parameters.AddWithValue("un",u_id);
SqlDataAdapter reader = cmd.ExecuteReader();
if (reader.Read() == false)
{
label1.Text = "用户不存在";
return;
}
string realpwd = reader.GetString(1);
if (u_pwd == realpwd)
{
label1.Text = "登录成功";
textBox1.Text = "";
textBox2.Text = "";
}
else
{
label1.Text = "登陆失败";
}
cmd.Dispose();
conn.Dispose();

为什么 无法将类型“System.Data.SqlClient.SqlDataReader”隐式转换为“System.Data.SqlClient.SqlDataAdapter”

Answer 1

SqlDataAdapter reader = cmd.ExecuteReader();这一句中的SqlDataAdapter 修改成

SqlDataReader

追问

弄好了，谢谢哈

追答

呵呵

Answer 2

应该是sqldatareader而不是adapter

Answer 3

SqlDataAdapter reader = cmd.ExecuteReader();//改为var reader = cmd.ExecuteReader();

追问

找不到类型或命名空间名称“var”(是否缺少 using 指令或程序集引用?)

出现这个问题怎么改？