using System;
Using System. Collections. Generic;
Using System.Com ponentModel;
Using System. The Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

Using System. The Data. SqlClient.

The namespace StudentInfoSystem
{
Public partial class frmLogin: Form
{
Public frmLogin ()
{
InitializeComponent ();
}

Public static string userName;//record login user name//main form used in
Public static string userRight;//record login user permissions//main form used in

SqlConnection conn.
SqlCommand com;
SqlDataAdapter da;
SqlDataReader Dr;
Private void frmLogin_Load (object sender, EventArgs e)
{

Try
{
Conn=new SqlConnection (" server=(local) \ \ sqlexpress; Integrated security=true; The database=StudentBC ");
The DataSet ds=new DataSet ();
Da=new SqlDataAdapter (" select user name from the user table ", conn);
If (conn. State==ConnectionState. Closed)
{
Conn. The Open ();
}
Da. The Fill (ds, "user list");
Conn. Close ();
CbxUserName. The DataSource=ds. The Tables (" user list "),
CbxUserName. DisplayMember="user name";
}
The catch (Exception ex)
{
MessageBox. Show (ex. Message. The ToString ());
}
}

Private void cbxUserName_SelectedIndexChanged (object sender, EventArgs e)//query permission values
{
Try
{
Com=new SqlCommand (" select the user name, user permissions from the users table where user name='" + cbxUserName. Text + "' ", conn);
If (conn. State==ConnectionState. Closed)
{
Conn. The Open ();
}
Dr=com. ExecuteReader ();



If (Dr. Read ())


{
LblUserRight1. Text=Dr [r]. "user rights" ToString ();
UserRight=lblUserRight1. Text;
}
Dr. Close ();
Conn. Close ();
}
The catch (Exception ex)
{
MessageBox. Show (ex. Message. The ToString ());
}
}

Private void btnLogin_Click (object sender, EventArgs e)//you can use the reader can also use data set class implements the
{
//data set class implements the
Try
{
Da=new SqlDataAdapter (" select * from the users table where user name='" + cbxUserName. Text. The Trim () + "' and the user password='" + txtUserPwd. Text. The Trim () + "' ", conn);
The DataSet ds=new DataSet ();
If (conn. State==ConnectionState. Closed)
{
Conn. The Open ();
}
Da. The Fill (ds, "user list");
Conn. Close ();
If (ds) Tables [r]. "the user table" Rows. Count & gt; 0)
{
The userName=cbxUserName. Text;

FrmMain frmMain=new frmMain ();
This. Hide ();
Frmmain. The Show ();
}
The else
{
MessageBox. Show (" the user name or password error!" , "tip", MessageBoxButtons. OK, MessageBoxIcon. Information);
TxtUserPwd. Text="";
CbxUserName. Focus ();
}
}
The catch (Exception ex)
{
MessageBox. Show (ex. Message. The ToString ());
}
}
//reader class implements the


Private void btnExit_Click (object sender, EventArgs e)
{
Application. The Exit ();
}

Private void frmLogin_FormClosed (object sender, FormClosedEventArgs e)
{
Application. The Exit ();
}

Private void frmLogin_Load_1 (object sender, EventArgs e)
{

}



}
}

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