根据组合框选择 C# 更改组合框值

Question

我一直在研究并尝试所有不同的方法来尝试让我的所有组合框的值在每次选择新选择时根据第一个特定组合框中的值进行更改。

以下是我使用过的代码，但在 ')' 附近不断出现错误语法无效

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data.SqlClient;
using System.Configuration;
using MaterialDesignColors;
using MaterialDesignThemes;
using System.Management;
using System.Windows.Forms;
using System.Data;
using ToolTip = System.Windows.Controls.ToolTip;

namespace SolAquaPro
{
    public partial class FuelEntry : Form
    {
        readonly SqlConnection conn1 = new SqlConnection();
        readonly SqlCommand cmd1 = new SqlCommand();
        SqlDataReader dr1;

        readonly SqlConnection conn3 = new SqlConnection();
        readonly SqlCommand cmd3 = new SqlCommand();
        SqlDataReader dr3;

        readonly SqlConnection conn6 = new SqlConnection();
        readonly SqlCommand cmd6 = new SqlCommand();
        SqlDataReader dr6;

        public FuelEntry()
        {
            InitializeComponent();
            conn1.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString.ToString();
            conn3.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString.ToString();
            conn6.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString.ToString();
        }

        private void BtnClose_Click(object sender, EventArgs e)
        {
            this.Close();
            Form frmFuelDash = new FuelDash();
            frmFuelDash.Show();
        }

        private SqlDataReader GetDr1()
        {
            return dr1;
        }

        private void FuelEntry_Load(object sender, EventArgs e)
        {
            conn1.Open();
            conn3.Open();

            cmd1.Connection = conn1;

            cmd1.CommandText = @"SELECT FleetNo, Driver, Registration, Company, Category, Target, Unit, FuelAcc, FuelRef, 
                                FuelDepot FROM tblFleetSetups WHERE (((tblFleetSetups.FleetCat)<>'Trailer' And 
                                (tblFleetSetups.FleetCat)<>'Retired'));";

            dr1 = cmd1.ExecuteReader();

            // TODO: This line of code loads data into the 'solAquaProjectMasterDataDataSet4.tblFuelDepots' table. You can move, or remove it, as needed.
            this.tblFuelDepotsTableAdapter.Fill(this.solAquaProjectMasterDataDataSet4.tblFuelDepots);
            // TODO: This line of code loads data into the 'solAquaProjectMasterDataDataSet3.tblFuelAccs' table. You can move, or remove it, as needed.
            this.tblFuelAccsTableAdapter.Fill(this.solAquaProjectMasterDataDataSet3.tblFuelAccs);
            // TODO: This line of code loads data into the 'solAquaProjectMasterDataDataSet2.tblCompanies' table. You can move, or remove it, as needed.
            this.tblCompaniesTableAdapter.Fill(this.solAquaProjectMasterDataDataSet2.tblCompanies);
            // TODO: This line of code loads data into the 'solAquaProjectMasterDataDataSet1.tblDrivers' table. You can move, or remove it, as needed.
            this.tblDriversTableAdapter.Fill(this.solAquaProjectMasterDataDataSet1.tblDrivers);
            // TODO: This line of code loads data into the 'solAquaProjectMasterDataDataSet.tblFleetSetups' table. You can move, or remove it, as needed.
            this.tblFleetSetupsTableAdapter.Fill(this.solAquaProjectMasterDataDataSet.tblFleetSetups);

            cboCompany.SelectedIndex = -1;
            cboDepot.SelectedIndex = -1;
            cboDriver.SelectedIndex = -1;
            cboFuelAcc.SelectedIndex = -1;
            cboFleetNo.SelectedIndex = -1;

            txtCategory.Text = "";
            txtFuelRef.Text = "";
            txtReg.Text = "";
            txtTarget.Text = "";
            txtUnit.Text = "";
        }

        private void BtnAdd_MouseHover(object sender, EventArgs e)
        {
            ToolTip tip = new ToolTip();
            tip.Content = "Add Fuel Entry";
        }

        private void BtnUndo_MouseHover(object sender, EventArgs e)
        {
            ToolTip tip = new ToolTip();
            tip.Content = "Reset To Blank Entry";
        }

        private void BtnProcess_MouseHover(object sender, EventArgs e)
        {
            ToolTip tip = new ToolTip();
            tip.Content = "Go To Fuel Entry Processing";
        }

        private void BtnClose_MouseHover(object sender, EventArgs e)
        {
            ToolTip tip = new ToolTip();
            tip.Content = "Close Form";
        }

        private void CboFleetNo_TextChanged(object sender, EventArgs e)
        {
            if (cboFleetNo.SelectedIndex == -1)
            {
                cboCompany.SelectedIndex = -1;
                cboDepot.SelectedIndex = -1;
                cboDriver.SelectedIndex = -1;
                cboFuelAcc.SelectedIndex = -1;

                txtCategory.Text = "";
                txtFuelRef.Text = "";
                txtReg.Text = "";
                txtTarget.Text = "";
                txtUnit.Text = "";
            }

            else if ((cboFleetNo.SelectedIndex != -1) && (isMatch(cboFleetNo.Text.ToString())))
            {
                txtReg.Text = dr1.GetValue(2).ToString();
                txtTarget.Text = dr1.GetValue(5).ToString();
                txtUnit.Text = dr1.GetValue(6).ToString();
                cboCompany.Text = dr1.GetValue(3).ToString();
                cboDepot.Text = dr1.GetValue(9).ToString();
                cboDriver.Text = dr1.GetValue(1).ToString();
                cboFuelAcc.Text = dr1.GetValue(7).ToString();
                txtCategory.Text = dr1.GetValue(4).ToString();

                conn6.Close();
            }
        }

        private void CboFuelAcc_TextChanged(object sender, EventArgs e)
        {

            if (cboFuelAcc.SelectedIndex == -1)
            {
                txtFuelRef.Text = "";
            }

            else if (cboFuelAcc.SelectedIndex != -1)
            {
                string FuelAcc = cboFuelAcc.Text.ToString();
                conn3.Close();
                conn3.Open();

                cmd3.Connection = conn3;
                cmd3.CommandText = @"SELECT [FuelAcc] ,[FuelRef] 
                                FROM [dbo].[tblFuelAccs] 
                                WHERE FuelAcc = '" + FuelAcc + "';";

                dr3 = cmd3.ExecuteReader();
                dr3.Read();

                txtFuelRef.Text = dr3.GetValue(1).ToString();

                conn3.Close();
            }
        }

        private bool isMatch(string iMatch)
        {
            iMatch = cboFleetNo.Text.ToString();
            conn6.Close();
            conn6.Open();
            cmd6.Connection = conn6;
            cmd6.CommandText = @"SELECT 1 FleetNo, Driver, Registration, Company, Category, Target, Unit, FuelAcc, FuelRef, 
                                FuelDepot FROM tblFleetSetups WHERE (((tblFleetSetups.FleetCat)<>'Trailer' And 
                                (tblFleetSetups.FleetCat)<>'Retired') And (tblFleetSetups.FleetNo)= '" +@iMatch+ "'));";
            dr6 = cmd6.ExecuteReader();

            if (dr6.Read())
            {
                if (Convert.ToBoolean(dr6["FleetNo"]) == true)
                {
                    return true;
                }

                else
                {
                    return false;
                }
            }

            else
            {
                return false;
            }
        }
    }
}

我们将不胜感激。

Answer 1

这意味着您的 SQL 查询存在语法错误。

其实这部分代码多了一个')'：(tblFleetSetups.FleetCat)<>'Retired').

确切的代码应该是：

cmd6.CommandText = @"SELECT 1 FleetNo, Driver, Registration, Company, Category, Target, Unit, FuelAcc, FuelRef, 
                            FuelDepot FROM tblFleetSetups WHERE (((tblFleetSetups.FleetCat)<>'Trailer' And 
                            (tblFleetSetups.FleetCat)<>'Retired' And (tblFleetSetups.FleetNo)= '" +@iMatch+ "'));";
      

Answer 2

cmd6.CommandText 似乎完全错误，错误似乎出在 SQL 部分，所以....试试：

cmd6.Parameters.Add(new SqlParameter("iMatch", iMatch));
cmd6.CommandText = @"SELECT 1 FleetNo, Driver, Registration, Company, Category, Target, Unit, FuelAcc, FuelRef, 
                            FuelDepot FROM tblFleetSetups WHERE (((tblFleetSetups.FleetCat)<>'Trailer' And 
                            (tblFleetSetups.FleetCat)<>'Retired') And (tblFleetSetups.FleetNo)= @iMatch);";

注意参数化的 SQL 命令，您需要在所有命令中执行此操作，是的，需要