Question

我有两个列表框。我可以通过文本框将值添加到一个列表框中。从此列表框中，我通过单击添加按钮将所需的值添加到listbox2。

现在我无法了解如何将第二个列表框中的值添加到名为Machines的数据库表中。这些值会添加到不同的行中。

Listbox2

PC1 

PC2

PC3

并将这些添加到数据库表机器

请帮帮我

这是将值从一个列表框传递到其他...的代码...

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections;
using System.Data.SqlClient;
using System.IO;

namespace WebApplication3
{
    public partial class WebForm2 : System.Web.UI.Page
    {
        ArrayList lasset = new ArrayList();
        ArrayList lsubordinate = new ArrayList();
        static ArrayList UpdateList = new ArrayList();
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        protected void ListBox2_SelectedIndexChanged(object sender, EventArgs e)
        {

        }
        //add one by one//
        protected void Button4_Click(object sender, EventArgs e)
        {
            if (ListBox1.SelectedIndex >= 0)
            {
                for (int i = 0; i < ListBox1.Items.Count; i++)
                {
                    if (ListBox1.Items[i].Selected)
                    {
                        if (!lasset.Contains(ListBox1.Items[i]))
                        {
                            lasset.Add(ListBox1.Items[i]);
                        }
                    }
                }
                for (int i = 0; i < lasset.Count; i++)
                {
                    if (!ListBox2.Items.Contains(((ListItem)lasset[i])))
                    {
                        ListBox2.Items.Add(((ListItem)lasset[i]));
                    }
                    ListBox1.Items.Remove(((ListItem)lasset[i]));
                }
            }
        }
        //Add all
        protected void Button5_Click(object sender, EventArgs e)
        {
            while (ListBox1.Items.Count != 0)
            {
                for (int i = 0; i < ListBox1.Items.Count; i++)
                {
                    if (!lasset.Contains(ListBox1.Items[i]))
                    {
                        lasset.Add(ListBox1.Items[i]);
                    }
                }
                for (int i = 0; i < lasset.Count; i++)
                {
                    if (!ListBox2.Items.Contains(((ListItem)lasset[i])))
                    {
                        ListBox2.Items.Add(((ListItem)lasset[i]));
                    }
                    ListBox1.Items.Remove(((ListItem)lasset[i]));
                }
            }
                    }
        //remove from listbox2 and add to listbox1//
        protected void Button6_Click(object sender, EventArgs e)
        {
            if (ListBox2.SelectedItem != null)
            {
                for (int i = 0; i < ListBox2.Items.Count; i++)
                {
                    if (ListBox2.Items[i].Selected)
                    {
                        if (!lsubordinate.Contains(ListBox2.Items[i]))
                        {
                            lsubordinate.Add(ListBox2.Items[i]);
                        }
                    }
                }
                for (int i = 0; i < lsubordinate.Count; i++)
                {
                    if (!ListBox1.Items.Contains(((ListItem)lsubordinate[i])))
                    {
                        ListBox1.Items.Add(((ListItem)lsubordinate[i]));
                    }
                    ListBox2.Items.Remove(((ListItem)lsubordinate[i]));
                    UpdateList.Add(lsubordinate[i]);
                }
            }

        }
        //remove all
        protected void Button7_Click(object sender, EventArgs e)
        {
            while (ListBox2.Items.Count != 0)
            {
                for (int i = 0; i < ListBox2.Items.Count; i++)
                {
                    if (!lsubordinate.Contains(ListBox2.Items[i]))
                    {
                        lsubordinate.Add(ListBox2.Items[i]);
                    }
                }
                for (int i = 0; i < lsubordinate.Count; i++)
                {
                    if (!ListBox1.Items.Contains(((ListItem)lsubordinate[i])))
                    {
                        ListBox1.Items.Add(((ListItem)lsubordinate[i]));
                    }
                    ListBox2.Items.Remove(((ListItem)lsubordinate[i]));
                    UpdateList.Add(lsubordinate[i]);
                }
            }
        }

Answer 1

您在评论中提供了此代码。

myConn.Open();
OleDbCommand dataCommand = new OleDbCommand();
if (ListBox2.Items.Count > 0) {
    foreach (ListItem i in ListBox2.Items) {
        insertContractCmd = ("insert into table column1) values ('"
                            + ListBox2.Items
                            + "')", myConn);
        }
    }
    myConn.Open();
    dataCommand.ExecuteNonQuery();
}

我发现代码有三个问题：

首先，insert命令中的括号不匹配。将("insert into table column1)更改为"insert into table (column1)

其次，您打开连接两次。丢失第二个myConn.Open();

第三，这是最大的问题 - 您正在尝试将字符串与整个项目列表连接起来。你应该做的是分别连接每个项目，如下所示：

// note: this is a bad example, use the next one instead
insertContractCmd = "insert into table (column1) values (";
foreach (ListItem item in ListBox2.Items) {
    insertContractCmd = insertContractCmd + "'" + item.Text + "'";
}
insertContractCmd = insertContractCmd + ")";

现在你只需处理一个小问题 - 这段代码很糟糕，因为它会导致很多字符串连接效率低下并占用大量内存。您应该使用StringBuilder代替：

StringBuilder commandBuilder = new StringBuilder("insert into table (column1) values (");
foreach (ListItem item in ListBox2.Items) {
    commandBuilder.AppendFormat("'{0}'", item.Text);
}
commandBuilder.Append(")");
insertContractCmd = commandBuilder.ToString();

注意：出于同样的效率原因，我也使用了AppendFormat。您也可以使用commandBuilder.Append("'" + item.Text + "'");来达到同样的效果。

希望有所帮助，configurator。

列表框值到数据库

1 个答案: