从数据表填充文本框 [英] fill text box from datatable

问题描述

在我的Windows窗体中，当从cmbjobecode中选择一个jobecode时，我有两个组合框和一个文本框，它将加载具有相应引号的cmbquotationcode并用选定的报价量填充文本框txtamount

一切都很好，除了我无法使文本框充满数量之外，任何人都可以帮助您排序错误

In my windows form i have two combobox and one text box when a jobecode is selected from cmbjobecode it will load cmbquotationcode with corresponding quotations and fills a textbox txtamount with amount of selected quotation

all is fine except i cannot get the textbox filled with the amount can anyone help in sorting mistake

 private void cmbjobcode_SelectedIndexChanged(object sender, EventArgs e)
        {
            comboQuotationboxload();
        }

public void comboQuotationboxload()
        {

            OleDbConnection oleDbConnection1 = new System.Data.OleDb.OleDbConnection(connString);
            oleDbConnection1.Open();

            OleDbCommand oleDbCommand1 = new System.Data.OleDb.OleDbCommand("Select quotationpk ,quotationcode , amount from  quotationmastertable  where jobpk = " + cmbjobcode.SelectedValue + "", oleDbConnection1);



            OleDbDataReader reader = oleDbCommand1.ExecuteReader();

            DataTable dt = new DataTable();
            dt.Columns.Add("quotationpk", typeof(int));
            dt.Columns.Add("quotationcode", typeof(string));
            dt.Columns.Add("amount", typeof(int));
            dt.Load(reader);
            cmbQuotationcode.ValueMember = "quotationpk";
            cmbQuotationcode.DisplayMember = "quotationcode";
            cmbQuotationcode.DataSource = dt.DefaultView;
            txtamount.text= "amount";


            oleDbConnection1.Close();

        }

推荐答案

第一件事.您应该真正使用参数化查询！如果选择的cmrjobcode值是什么呢? --drop表用户:)
您可以按照以下步骤进行操作:

First things first. You should REALLY use Parameterized Queries! What if the selected value of cmrjobcode was something like ; --drop table users :)
You can do this as follows:

OleDbCommand oleDbCommand1 = new System.Data.OleDb.OleDbCommand("Select quotationpk ,quotationcode , amount from  quotationmastertable  where jobpk = @jobpk", oleDbConnection1);
oleDbCommand1.Parameters.AddWithValue("@jobpk", cmbjobcode.SelectedValue);

用提供给 ^ ]. oledbcommand.parameters.aspx>命令的参数集合 [ ^ ].
现在，您的代码更易于阅读，查询可能会执行得更快(参数化查询会带来一些性能提升)，并且您的代码是 SQL注入 [^ ]安全！
其次，如果implement IDisposable ，则您应该真正将objects中的dispose > [< ^ ].连接和命令对象就是这种情况.您可以使用使用关键字 [oleDbCommand1.Dispose [.我确定您希望做的是放入当前选择的 DataRow [ ^ ]来自您的数据表 [TextBox.Text [ ^ ].
您可能应该做的是创建一个 BindingSource [ ^ ]并将您的数据表分配给 ^ ].现在，您可以将ComboBox的DataSource设置为指向BindingSource，然后可以添加 ^ ]使用 ^ ](继承自控件 [^ ]).您可以在设计器中设置大多数属性.
在您的代码中只需添加:

This will replace any parameter in your query string (in this case @jobpk) with the value of the object provided to the AddWithValue Method[^] of your Parameter collection of your Command[^].
Your code is now better to read, your query will possibly execute faster (parameterized queries have some performance gain) and your code is Sql Injection[^] safe!
Second, you should really dispose of your objects if they implement IDisposable[^]. This is the case for you connection and command objects. You can do this using the using keyword[^] or by calling oleDbConnection1.Dispose and oleDbCommand1.Dispose[^].
Also, you should better name your variables and objects. For example, cmbjobcode is hard to read. cmbJobCode reads much better!

Now to answer your question, you are currently simply setting the text to the literal string "amount". What I am sure you wish to do is put the amount of the currently selected DataRow [^]from your DataTable[^] in the TextBox.Text[^].
What you should probably do is create a BindingSource[^] and assign your DataTable to the DataSource Property[^]. You can now set the DataSource of your ComboBox to point at the BindingSource and you can add a Binding[^] to your TextBox using TextBox.DataBindings[^] (Inherited from Control[^]). You can set most of the properties in your designer.
In your code just add:

bindingSource.DataSource = dt;

我认为应该可以解决问题.祝你好运！ :)

I think that should do the trick. Good luck! :)

最终我做到了

txtamount.text = dt.Rows [0] cells [2] .Tostring();

finally I did it

txtamount.text= dt.Rows[0]cells[2].Tostring();

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