Question

public static void DeleteThreads(int threadID)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("DELETE FROM dbo.Threads");
    sb.Append(" WHERE ThreadsID=@ThreadsID");

    string myConnectionString = AllQuestionsPresented.connectionString;

    using (SqlConnection myConnection = new SqlConnection(myConnectionString))
    {
        myConnection.Open();
        SqlCommand sqlCommand = new SqlCommand(sb.ToString(), myConnection);
        sqlCommand.Parameters.Add("@ThreadsID", SqlDbType.Int);
        sqlCommand.Parameters["@ThreadsID"].Value = threadID;
        sqlCommand.ExecuteNonQuery();

    }
}

It gives me this Error:

The DELETE statement conflicted with the REFERENCE constraint "FK_Comments_Threads". The conflict occurred in database "model", table "dbo.Comments", column 'ThreadsID'.

The statement has been terminated.

Should this fix that error:

enter code here  public static void DeleteComments(int threadID)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("DELETE FROM dbo.Comments");
    sb.Append(" WHERE ThreadsID=@ThreadsID");

    string myConnectionString = AllQuestionsPresented.connectionString;

    using (SqlConnection myConnection = new SqlConnection(myConnectionString))
    {
        myConnection.Open();
        SqlCommand sqlCommand = new SqlCommand(sb.ToString(), myConnection);
        sqlCommand.Parameters.Add("@ThreadsID", SqlDbType.Int);
        sqlCommand.Parameters["@ThreadsID"].Value = threadID;
        sqlCommand.ExecuteNonQuery();

    }
}

Answer 1

You don’t have a space, and it looks like you’re missing the FROM keyword.

Try:

sb.Append("DELETE FROM dbo.Threads");    
sb.Append(" WHERE ThreadsID=@ThreadsID");

Also, for the record: Using inline SQL is generally bad due to tightly coupling your application to your database. You should use a separate data access layer if this application is for any serious purpose.