用户登陆代码问题
try
{
string myconn= "Integrated Security=SSPI;User Id=sa;database=jindu2;server=localhost ";
SqlConnection myconnection=new SqlConnection (myconn);
myconnection.Open();//打开数据库连接
string usname= "select * from userinfo where username= "+textBox1.Text + " and password= "+textBox2.Text + " ";
SqlCommand cmdd = new SqlCommand(usname, myconnection);
SqlDataReader myreader=cmdd.ExecuteReader();
if(myreader.Read ())
{
Form1 form1=new Form1 ();
form1.Show ();
this.Dispose ();
}
else
MessageBox.Show ( "你输入的密码不正确,请重新输入 ");
myreader.Close ();
myconnection.Close ();
}

catch(Exception ex)
{
MessageBox.Show (ex.ToString());
}

输入用户名和密码总是提示列名无效,比如用户名li,密码123,则提示列名 'li '无效,列名 '123 '无效
这是什么错误呢,请高手指教

[解决办法]
少引号了！

string usname= "select * from userinfo where username= ' "+textBox1.Text + " ' and password= ' "+textBox2.Text + " ' ";

[解决办法]
string usname = "select * from userinfo where username = ' "+textBox1.Text + " ' and password = ' "+ textBox2.Text + " ' ";

为什么不用参数 or 存储过程?