Window form datagridview selected the first row from databinding source if the textBox1 send the null value but i want to set that if textBox1 send it the null value to binding source then databinding source Row selection =false

Window form datagridview selected the first row from databinding source if the textBox1 send the null value but i want to set that if textBox1 send it the null value to binding source then databinding source Row selection =false

and if textBox1!= null then databinding source Row selection mode =true