insert into table using combo Box dev express when use change editor GridLookUpEdit

Question

I have an information entry form that I want this information to be stored in a table, and I have a combo box whose information is read from the bank, but when saving the id of the combo box, it is not saved in the table I want and gives an error

and this is error when click save button

System.Data.SqlClient.SqlException: 'Incorrect syntax near '2'.'

fill combo box
`//fill area
            var data_area = SQLHelper.ExecQueryDataAsDataTable("select  idunit, Area from pi_unit");
            cbara.Properties.DataSource = data_area;
            cbara.Properties.ValueMember = "idUnit";
            cbara.Properties.DisplayMember = "Area";`

this is sql connection and insert into command:

  string query = "insert into 
Pi_Line_No(idUNIT,Line,Line_Size,Circuit,Serial,Pipe_Class) values("+idUNIT+",'"+Line+"','"+Size+"','"+Circuit+"','"+Serial+"','"+PipeClass+"')";

            using (SqlConnection connection = new SqlConnection("/* connection info */"))
            {
                using (SqlCommand command = new SqlCommand(query, connection))
                {
                    connection.Open();
                    command.ExecuteNonQuery();
                }
            }

I want the form information to be saved in the table, but a combo box gives an error when saving.