Assume that a page named ProductDetail.aspx has a detailview whose content includes : ProductID,ProductName,Price,Category.
We can insert new product from detailview directly(Enable inserting).
This is my question:
If I insert a new ProductID which has exists in database , a message error will be thrown.How I can do that ?
Thanks.

Hi there.. You are asking how to throw the error or how to detect if the product exists?

HTH

Gonzalo

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You can do like this.

When you want to insert a new product into database,you can check whether it is exist.

public void BtnAdd_Click(object sender,EventArgs e){
  if(dao.isExists(productId)){
    //print error msg.
  }else{
    //add new product.
  }
}