Error CS0234 The type or namespace name 'Reporting' does not exist in the namespace 'Microsoft' (Are you missing an assembly reference?)

Question

I downloaded this project and database but when I run it I get this error, Can you please help me to fix this? I really appreciate your help.

I have attached the source code and database, please take a look. https://gofile.io/d/9TZvQV Thank you!

enter image description here

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using Microsoft.Reporting.WinForms;

namespace DBApplication
{
    public partial class frmBilling : Form
    {
        SqlConnection con;
        SqlDataAdapter da;
        SqlCommand com;
        SqlDataReader dreader;
        DataSet ds;
        DataTable dt;
        DataRow dr;
        string sql;
        int quantity;
        ReportDataSource rds;
        ReportParameterCollection repParams;
        public frmBilling()
        {
            InitializeComponent();
            string constr = ConfigurationManager.ConnectionStrings["constr"].ToString();
            con = new SqlConnection(constr);
            loadCategory();
        }

        private void loadCategory()
        {
            sql = "SELECT CategoryID,CategoryName FROM Categories";
            da = new SqlDataAdapter(sql, con);
            ds = new DataSet();
            da.Fill(ds, "Categories");
            dt = ds.Tables["Categories"];
            dr = dt.NewRow();
            dr[0] = "-1";
            dr[1] = "--Select Category--";
            dt.Rows.InsertAt(dr, 0);
            cmbCategory.DisplayMember = "CategoryName";
            cmbCategory.ValueMember = "CategoryID";
            cmbCategory.DataSource = dt;
        }

Answer 1

Based on the advice from Michael and my test on your project, please install -nuget package Microsoft.Reporting.WinForms.v11 to solve your problem.