我创建了一个程序,该程序将入住酒店并更新后端。我在连接和更改会议室桌上的用户 ID 时遇到问题。表格是:
用户:
UserID - PK, Auto Number
Username - Short Text
Password - Short Text
房间
RoomID - PK, Auto Number
Room_Number - Number
UserID - FK, Number
可更新查询
PARAMETERS parUsername Short, parRoom_Number Short;
UPDATE Rooms SET UserID = (SELECT UserID FROM Users WHERE Username = [parUsername])
WHERE Room_Number=[parRoom_Number];
C# 代码
表格1
MessageBox.Show("Login Successful");
Home home = new Home();
home.Show();
home.LabelText = this.txtUsername.Text;
主页表格
public string LabelText
{
get
{
return this.lblUsername.Text;
}
set
{
this.lblUsername.Text = value;
}
}
签入用户控件
Home home = new Home();
try
{
string ConnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Application.StartupPath + "/Hotel.accdb";
using (var con = new OleDbConnection(ConnString))
{
con.Open();
using (var cmd = new OleDbCommand())
{
cmd.Connection = con;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "Query2";
cmd.Parameters.Add("parUsername", home.LabelText);
cmd.Parameters.Add("parRoom_Number", lbRooms.SelectedItem);
cmd.ExecuteNonQuery();
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
不要使用子查询,请尝试以下操作
PARAMETERS parUsername Text ( 255 ), parRoom_Number Long;
UPDATE Rooms, Users SET Rooms.UserID = Users.UserID
WHERE Rooms.Room_Number = [parRoom_Number] AND Users.Username = [parUsername];
首先,我更改了 Query2 存储过程。传递用户 ID 和房间号(将其更改为数字数据类型以匹配表定义(而不是像您的问题中那样的短。
PARAMETERS parUserID Number, parRoom_Number Number;
UPDATE Rooms SET UserID = [parUserID]
WHERE Room_Number=[parRoom_Number];
然后,我将代码修改为单独的查询以获取 UserId。
Home home = new Home();
int userID;
try
{
string ConnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Application.StartupPath + "/Hotel.accdb";
using (var con = new OleDbConnection(ConnString))
{
con.Open();
//Passing the query and the connection directly to the constructor
using (OleDbCommand cmd1 = new OleDbCommand("SELECT UserID FROM Users WHERE Username = @UserName;", con))
{
cmd1.Parameters.Add("@UserName", OleDbType.VarChar).Value = home.LabelText;
userID = (int)cmd1.ExecuteScalar();
}
using (var cmd = new OleDbCommand())
{
cmd.Connection = con;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "Query2";
cmd.Parameters.Add("parUserID", OleDbType.Numeric).Value = userID;
cmd.Parameters.Add("parRoom_Number",OleDbType.Numeric ).Value = (int)lbRooms.SelectedItem;
cmd.ExecuteNonQuery();
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
请尝试
以下选项,它应该可以工作
UPDATE Rooms A,(SELECT UserID FROM Users WHERE Username = 'Test') B SET A.UserID = B.UserID WHERE Room_Number=1;