如何在C＃中使用LINQ从sql数据库中找到重复项

Question

I have a method which will return duplicate records from database using sql command. The code is:

 public bool RecordExists(string name)
   {
       OleDbCommand cmd = new OleDbCommand("select count(*) from Demographics where thal_Id = '" + txtPtntSmpl.Text + "'", con);
       int recordCount = Convert.ToInt32(cmd.ExecuteScalar());
       cn.Close();
       return recordCount > 0;
   } 

According to this ,If I call this method in textbox leave event I will raise an error while duplicate records occurs from database. Now I want the same operation by using linq . Please anyone help me. Thanking you

Answer 1

Assuming you have a List of Demographic and you want to see how many match a certain text value, try something like this:

 public bool RecordExists(string name)
   {
       List<Demographic> demographics = PopulateList();

       return demographics.Count(d => d.thal_Id == name) > 0;
   } 

Answer 2

If you use Linq to SQL, having dc as your data context, it should look smth like this:

public bool RecordExists(string id)
{
    return dc.Demographics.Any(d => d.thal_Id == id);
}