无法从字符串转换为int32

Question

我遇到了一个问题,我只能在单个文本框中从数据库中检索数据.我想要的是,我想从数据库中检索每个文本框的数据,但是当我尝试时,得到错误:

这是代码:

string connectionString = (@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=\Archives\Projects\Program\Sell System\Sell System\App_Data\db1.accdb;Persist Security Info=False;");

private List<List<TextBox>> textBoxCodeContainer = new List<List<TextBox>>();
private List<List<TextBox>> textBoxQuantityContainer = new List<List<TextBox>>();
private List<List<TextBox>> textBoxDescContainer = new List<List<TextBox>>();
private List<List<TextBox>> textBoxSubTotalContainer = new List<List<TextBox>>();
private List<List<TextBox>> textBoxTotalContainer = new List<List<TextBox>>();

private void Form1_Load(object sender, EventArgs e)
{  
    UpdateTextPosition();

    OleDbDataReader dReader;
    OleDbConnection conn = new OleDbConnection(connectionString);
    conn.Open();
    OleDbCommand cmd = new OleDbCommand("SELECT [Code] FROM [Data]", conn);

    dReader = cmd.ExecuteReader();

    AutoCompleteStringCollection codesCollection = new AutoCompleteStringCollection();

    while (dReader.Read())
    {
         string numString = dReader[0].ToString().PadLeft(4, '0');
         codesCollection.Add(numString);
    }

    dReader.Close();
    conn.Close();
}

private void UpdateDatas()
{    
    OleDbDataReader dReader;
    OleDbConnection conn = new OleDbConnection(connectionString);
    conn.Open();
    OleDbCommand cmd = new OleDbCommand("SELECT DISTINCT [Description], [Price] FROM [Data] WHERE [Code]=@Code", conn);

    cmd.Parameters.Add("Code", System.Data.OleDb.OleDbType.Integer);
    cmd.Parameters["Code"].Value = this.textBoxCodeContainer[0][0].Text;

    dReader = cmd.ExecuteReader();

    while (dReader.Read())
    {
        this.textBoxDescContainer[0][0].Text = dReader["Description"].ToString();
        this.textBoxSubTotalContainer[0][0].Text = dReader["Price"].ToString();
    }

    dReader.Close();
    conn.Close();
}

我已经尝试过添加:

cmd.Parameters.Add("Code", System.Data.OleDb.OleDbType.Integer);
cmd.Parameters["Code"].Value = this.textBoxCodeContainer[0][1].Text;

和

while (dReader.Read())
{
    this.textBoxDescContainer[0][1].Text = dReader["Description"].ToString();
    this.textBoxSubTotalContainer[0][1].Text = dReader["Price"].ToString();
}

但我得到一个错误,上面写着:"无法将参数值从字符串转换为int32"

Answer 1

尝试这个

您必须将字符串解析为Int32 DataType

cmd.Parameters.Add("Code", System.Data.OleDb.OleDbType.Integer);
cmd.Parameters["Code"].Value =int.Parse(this.textBoxCodeContainer[0][1].Text);

如果用户输入有效的整数，这应该有效

例如

int Val=int.Parse("45");//Works for me

注意：这不适用于十进制值

或者，如果您的Price值包含 Decimal，您可以做的是

cmd.Parameters["Code"].Value = Convert.ToInt32(Convert.ToDouble(this.textBoxCodeContainer[0][1].Text));

这应该有效