如何解决将数据类型varchar转换为数字的错误 [英] how to solve error of converting datatype varchar to numeric

问题描述

（当我尝试运行此代码时，它在da.Fill（dth）附近发出错误，将数据类型varchar转换为数字时出错。

(when i am trying to run this code it is giving an error near da.Fill(dth) that error converting data type varchar to numeric)

public partial class ministatement : Form
{
    SqlConnection connect = new SqlConnection(@"data source=ABHINAV-PC\ABHI;integrated security=true;initial catalog=ATM;");

   public ministatement()
   {
       InitializeComponent();
   }

    private void ministatement_Load(object sender, EventArgs e)
    {

         connect.Open();
SqlCommand cmd = new SqlCommand("select * from transactions where account_no='" + label4.Text +"'" , connect);
        DataTable dth = new DataTable();
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        da.Fill(dth);
        dataGridView1.DataSource = dth;
    }
}
}

推荐答案

改为使用参数化查询。

Use Parameterized query instead.

SqlCommand cmd = new SqlCommand("select * from transactions where account_no=@AccountNo" , connect);

cmd.Parameters.Add(new SqlParameter("AccountNo", label4.Text))

您的错误似乎是''的用法。如果您的数据库文件是数字，则应使用不带''的值，如下例所示：

You error seems to be the usage of ' '. If your DB filed is numeric you should use the value without ' ' like in the next example:

SqlCommand cmd = new SqlCommand("select * from transactions where account_no=" + label4.Text, connect);

更好的是从UI元素中获取您的值（在您的情况下为label.Text），然后在SQlCommand中使用它：

Better is to get your value from UI element (in your case label.Text), then use it in the SQlCommand:

SqlCommand cmd = new SqlCommand(string.Format("select * from transactions where account_no={0}", yourValue), connect);

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