Some doubt in retrive the particular id

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C#

I DESIGN A small application as follows;

Project ID Combobox1
Project Name Textbox1
Rate Textbox2
Unit Textbox3
Amt Textbox4

all the datas are stored in the database.

I have one textbox and one button(button name Project Wise Id)in textbox i type the letter R Only the project id start with R want to display the output as follows;

Project ID Project Name Rate Unit Amt
R001 Embedded 30 16 480
R002 Embedded 40 16 640
1120

Project ID Project Name Rate Unit Amt
P001 JAva 15 5 75
P002 .Net 20 10 200
R001 Embedded 30 16 480
R002 Embedded 40 16 640
Total 1395

private void button3_Click(object sender, EventArgs e)
        {
            con = new SqlConnection("Server=(local);initial catalog=master;Trusted_Connection=True");
            con.Open();
            string str = "select * from Project where PojectID like = '" + cb_id.SelectedItem + "'";
            SqlCommand com = new SqlCommand(str, con);
            SqlDataAdapter sqlda = new SqlDataAdapter(com);
            DataSet ds = new DataSet();
            sqlda.Fill(ds, "Project");
            con.Close();

            ReportDocument r1 = new ReportDocument();
            //r1.Load("Full Path of Your Report\Employee.rpt");
            //string path = Server.MapPath("Reports/Service Bill.rpt");
            r1.Load("Reports/ProjectReport.rpt");
            r1.SetDataSource(ds);
            crystalReportViewer1.ReportSource = r1;
            crystalReportViewer1.RefreshReport();
 }

Here this query as follows: "select * from Project where PojectID like = '" + cb_id.SelectedItem + "'";

From the above please correct the query i have some doubt.

[Edit]Code block added[/Edit]