Incorrect syntax near ','. Description: An unhandled exception occurred during the execution

Question

I know this title seems to be repeated a lot but I tried to search and didn't find the answer.

Code:

using System;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e) {}

    protected void gv_master_SelectedIndexChanged(object sender, EventArgs e)
    {
        // Get the currently selected row using the SelectedRow property.
        GridViewRow row = gv_master.SelectedRow;

        // Display the first name from the selected row.
        // In this example, the third column (index 2) contains
        // the first name.
        lbl_reqNoV.Text = row.Cells[1].Text;
        lbl_reqNoV.Visible = true;
        lbl_reqNo.Visible = true;

        SqlConnection sqlConnection1 = new SqlConnection("Data Source=saitest01;Initial Catalog=SAI_website;Persist Security Info=True;User ID=sa;Password=sai@987");
        SqlCommand cmd = new SqlCommand();

        cmd.CommandText = "Select * from purchase Where ReqNo = '" + lbl_reqNoV.Text + "', sqlConnection1";

        cmd.CommandType = CommandType.Text;
        cmd.Connection = sqlConnection1;

        sqlConnection1.Open();
        SqlDataReader DR1;
        DR1 = cmd.ExecuteReader();
        DR1.Read();

        // Data is accessible through the DataDR1 object here
        gv_full.DataSource = DR1;
        gv_full.DataBind();
    }
}

Answer 1

the problem is you where adding the name of Connection in the query text which is ofcource not recognized by sqlserver the correct format was

var cmd = new SqlCommand("Select * from purchase Where ReqNo = @reqno",sqlConnection1)

or you can do this

cmd.CommandText = "Select * from purchase Where ReqNo = @reqno";

cmd.Parameters.AddWithValue("reqno",lbl_reqNoV.Text);
cmd.CommandType = CommandType.Text;
cmd.Connection = sqlConnection1;

you should always use parameters in query to avoid Sql Injection

Answer 2

just change following

 cmd.CommandText = "Select * from purchase Where ReqNo = '" + lbl_reqNoV.Text + "', sqlConnection1";

with,

 cmd.CommandText = "Select * from purchase Where ReqNo = '" + lbl_reqNoV.Text + "' ";

Above will make your code working. But you should modify you code to handle SQL Injection. As answered by @Usman