本文介绍了我收到错误“将数据类型 nvarchar 转换为实数时出错."的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!
问题描述
我的代码如下,请告诉我问题出在哪里,以便我们可以按仓库 ID 降价 7%?
The code which I have is below, can you please inform me where the issue might be so we can drop the price by warehouse ID with 7%?
private void button4_Click(object sender, EventArgs e)
{
try
{
myConnection = new SqlConnection(frm.cs);
myCommand = new SqlCommand("update Inventory set Price=@Price where WarehouseCode=6", myConnection);
myConnection.Open();
myCommand.Parameters.AddWithValue("@Price", "@Price * 0.7");
myCommand.ExecuteNonQuery();
myConnection.Close();
MessageBox.Show("Update successfully!");
DisplayData();
if (myConnection.State == ConnectionState.Open)
{
myConnection.Dispose();
}
}
推荐答案
当你的 仓库 ID
和 折扣率
由最终用户指定,我建议您的代码如下:
As you are not assigning any value to @Price
in the C# code while your Warehouse Id
and the Discount rate
are subject to be assigned by the end-user, I recommend your code be like this:
private void button4_Click(object sender, EventArgs e)
{
try
{
var discountRate = 0.07; //could be Convert.ToDouble(textBox1.Text) or something else
var warehouseId = 6; //again, could be Convert.ToInt32(textBox2.Text) or something else
myConnection = new SqlConnection(frm.cs);
myCommand = new SqlCommand("update Inventory set Price=Price*(1-@DiscountRate) " +
"where WarehouseCode=@WarehouseId", myConnection);
myConnection.Open();
myCommand.Parameters.AddWithValue("@DiscountRate", discountRate);
myCommand.Parameters.AddWithValue("@WarehouseId", warehouseId);
myCommand.ExecuteNonQuery();
myConnection.Close();
MessageBox.Show("Update successfully!");
DisplayData();
if (myConnection.State == ConnectionState.Open)
{
myConnection.Dispose();
}
}
catch
{
}
}
我还建议您重新考虑您的查询,因为它会使用相同的值更新所有产品价格,您可以考虑传递参数 @ProductId
并且您的查询是
I would also recommend you think again about your query as it will update all products price with the same value, you may consider passing parameter @ProductId
and your query be
update Inventory set Price=Price*(1-@DiscountRate)
where WarehouseCode=@WarehouseId and ProductCode=@ProductId
当然是这样.
这篇关于我收到错误“将数据类型 nvarchar 转换为实数时出错."的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!
本站部分内容来源互联网,如果有图片或者内容侵犯了您的权益,请联系我们,我们会在确认后第一时间进行删除!