Validate DropDownList and CheckBox in ASP.Net GridView using C#

Then you need to update the code.

First loop through the GridView rows and validate and update the isvalid variable.

After completion of GridView rows checking, again loop through the GridView rows and if valid and execute the stored procedure with parameter inside the loop.

Solved, thanks you, my new code below

private void MTH(ImageButton imgbtn)
{
    if (imgbtn != null)
    {
        bool isvalid = true;
        foreach (GridViewRow row in gvProducts.Rows)
        {
            CheckBox chk = (CheckBox)row.FindControl("chkRow");

            //I need pass this value on sProc
            string sp_1 = row.Cells[1].Text.ToString();

            string ddl_1 = ((DropDownList)row.FindControl("ddl_1")).Text;
            string ddl_2 = ((DropDownList)row.FindControl("ddl_2")).Text;
            string ddl_3 = ((DropDownList)row.FindControl("ddl_3")).Text;
            string txt = ((TextBox)row.FindControl("txt")).Text;

            if ((ddl_1.ToUpper() == "KO" || ddl_2.ToUpper() == "KO" || ddl_3.ToUpper() == "KO") && string.IsNullOrEmpty(txt))
            {
                Page.ClientScript.RegisterStartupScript(this.GetType(), "Alert", "alert('0 - KO');", true);
                isvalid = false;
                break;
            }
            else
            {
                if (chk.Checked && !string.IsNullOrEmpty(ddl_1) && !string.IsNullOrEmpty(ddl_2) && !string.IsNullOrEmpty(ddl_3))
                {
                    // Do the rest process.
                    isvalid = true;
                }
                else
                {   
                    isvalid = false;


                    Page.ClientScript.RegisterStartupScript(this.GetType(), "Alert", "alert('1 - KO');", true);
                }
            }
        }

        if (isvalid)
        {
           foreach (GridViewRow row in gvProducts.Rows)
           {				
               CheckBox chk = (CheckBox)row.FindControl("chkRow");

               //I need pass this value on sProc
               string sp_1 = row.Cells[1].Text.ToString();

               string ddl_1 = ((DropDownList)row.FindControl("ddl_1")).Text;
               string ddl_2 = ((DropDownList)row.FindControl("ddl_2")).Text;
               string ddl_3 = ((DropDownList)row.FindControl("ddl_3")).Text;
               string txt = ((TextBox)row.FindControl("txt")).Text;

            using (MySqlConnection myConnectionString =
                new MySqlConnection(ConfigurationManager.ConnectionStrings["cn"].ConnectionString))
            {
                using (MySqlCommand cmd = new MySqlCommand("sp_chkRow", myConnectionString))
                {
                    cmd.CommandTimeout = 2147483;
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.Parameters.Clear();

                    //I need pass this value on sProc
                    cmd.Parameters.AddWithValue("@sp_1", sp_1.ToString());

                    cmd.Parameters.Add(new MySqlParameter("@spSqlQuery", MySqlDbType.VarChar));
                    cmd.Parameters["@spSqlQuery"].Direction = ParameterDirection.Output;

                    cmd.Connection.Open();
                    cmd.ExecuteNonQuery();
                    cmd.Connection.Close();

                    string spSqlQuery = cmd.Parameters["@spSqlQuery"].Value.ToString();

                    Response.Write(spSqlQuery + "<br />");
                }
            }
        }
    }
}