C# 连接数据库 登录窗体，的代码，重要就是查询 用户名和密码的语句

C# 连接数据库 登录窗体，的代码，主要就是查询 用户名和密码的语句
RT

[解决办法]
建议，将数据连接放在App.config里：

C# code

<?xml version="1.0" encoding="utf-8" ?><configuration>  <configSections>  </configSections>  <connectionStrings>    <add name="【自定义连接名称 如：SQLDBConnectionString(数据库名称+ConnectionString)】"        connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\【数据库文件如：SqlDB.mdf】;Integrated Security=True;User Instance=True;Asynchronous Processing=true"        providerName="System.Data.SqlClient" />  </connectionStrings></configuration>
[解决办法]
登录按钮：
C# code
private void button1_Click(object sender, EventArgs e)        {            if ( textBox2.Text.Trim() == "" || textBox3.Text.Trim() == "")            {               MessageBox.Show("提示：请输入登录用户名和密码！", "警告");            }            else             {                              SqlConnection connect = DB.DB_Login();                string strSQL = "select * from 表名 where Login='" + textBox2.Text.Trim() + "'and Password='" + textBox3.Text.Trim() + "'";                SqlCommand cmd = new SqlCommand(strSQL, connect);                SqlDataReader asd = cmd.ExecuteReader();                asd.Read();                if (asd.HasRows)                {                   this.Hide();                   MainForm formchild = new MainForm();                   formchild.users = textBox2.Text.Trim();                   formchild.Show();                }                else                {                        MessageBox.Show("提示：学生用户名或密码错误！", "警告");                }                   connect.Close();                }                           }        }