1  public string AddUserN = ""; //定义用户名字符串  2         public string paswrd1 = "";  //密码1  3         public string paswrd2 = "";  //确认密码  4         public string userKind = ""; //用户类型  5         public string myconnstr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=ErLake.mdb";  6          7   8         private void 添加用户frm_Load(object sender, EventArgs e)  9         { 10  11             loadtable(); 12  13         } 14  15         private void button1_Click(object sender, EventArgs e) 16         { 17             userKind = comboBox1.Text.ToString();//获取用户类型 18             //MessageBox.Show(userKind); 19             AddUserN = textBox1.Text.Trim(); 20             paswrd1 = textBox2.Text.Trim(); 21             paswrd2 = textBox3.Text.Trim(); 22             if (userKind == "") 23             { 24                 MessageBox.Show("请选择添加的用户类型", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 25             } 26             else 27             { 28  29                 if (AddUserN == "") 30                 { 31                     MessageBox.Show("请填写用户名", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 32                 } 33                 else 34                 { 35                     string sql = "Select count(*) from tb_admin where 用户名='" + AddUserN + "'";//查询表里用户名为输入用户名的条数（有几条数据） 36                     OleDbConnection myconn = new OleDbConnection(myconnstr); 37                     //打开数据库 38                     myconn.Open(); 39                     //执行SQL 40                     OleDbCommand commd = new OleDbCommand(sql, myconn);// 41  42                     int n = (int)commd.ExecuteScalar();//得到条数 43                     myconn.Close();//关闭 44  45                     if (n >= 1)//存在 46                     { 47                         MessageBox.Show("该用户已存在！", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 48                     } 49                     else 50                     { 51                         if (paswrd1 == "") 52                         { 53                             MessageBox.Show("请填写用户密码", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 54                         } 55                         else 56                         { 57  58                             if (paswrd2 == "") 59                             { 60                                 MessageBox.Show("请填写确认的用户密码", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 61                             } 62                             else 63                             { 64                                 if (paswrd1 == paswrd2) 65                                 { 66                                     //插入字符串 67                                     string mySQL = "insert into tb_admin (用户名,权限,密码) values ('" + AddUserN + "','" + userKind + "','" + paswrd2 + "')"; 68                                     //创建连接实例 69                                     OleDbConnection myconn1 = new OleDbConnection(myconnstr); 70                                     //打开数据库 71                                     myconn1.Open(); 72                                     //执行SQL 73                                     OleDbCommand commd1 = new OleDbCommand(mySQL, myconn1);// 74                                     //写入 75                                     commd1.ExecuteNonQuery(); 76                                     //命令关闭连接 77                                     commd1.Connection.Close(); 78                                     //数据库关闭连接 79                                     myconn1.Close(); 80                                     // 81                                     MessageBox.Show("增加用户成功", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 82                                      83                                     loadtable();//加载用户信息表 84  85                                 } 86                                 else 87                                 { 88                                     MessageBox.Show("密码填写不一致，请重新填写", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information); 89                                 } 90                             } 91                         } 92                     } 93                 } 94             } 95         } 96  97         public void loadtable() 98         { 99             DataTable mytableall = new DataTable();100             string mysqlall = "select * from tb_admin ";101             OleDbDataAdapter da = new OleDbDataAdapter(mysqlall, myconnstr);//数据适配器102             da.Fill(mytableall);//填表103             dataGridView1.DataSource = mytableall;104         }