private void searchbtn_Click(object sender, EventArgs e) { DataTable dt = new DataTable(); if (Namecb.Text != "All" && categorycb.Text == "All" && authorcb.Text == "All") { dt = lc.searchBookbyTitle(Namecb.SelectedValue.ToString()); } else if (Namecb.Text == "All" && categorycb.Text != "All" && authorcb.Text == "All") { dt = lc.searchBookbyCategory(categorycb.SelectedValue.ToString()); } else if (Namecb.Text == "All" && categorycb.Text == "All" && authorcb.Text != "All") { dt = lc.searchBookByAuthor(authorcb.SelectedValue.ToString()); } else if (Namecb.Text != "All" && categorycb.Text != "All" && authorcb.Text == "All") { dt = lc.searchBookByTitleandCategory(Namecb.SelectedValue.ToString(), categorycb.SelectedValue.ToString()); } else if (Namecb.Text != "All" && categorycb.Text == "All" && authorcb.Text != "All") { dt = lc.searchBookByTitleandAuthor(Namecb.SelectedValue.ToString(), authorcb.SelectedValue.ToString()); } else if (Namecb.Text == "All" && categorycb.Text != "All" && authorcb.Text != "All") { dt = lc.searchBookByCategoryandAuthor(categorycb.SelectedValue.ToString(), authorcb.SelectedValue.ToString()); } else if (Namecb.Text != "All" && categorycb.Text != "All" && authorcb.Text != "All") { dt = lc.searchBookByTitleandCategoryandAuthor(Namecb.SelectedValue.ToString(), categorycb.SelectedValue.ToString(), authorcb.SelectedValue.ToString()); } else { dt = lc.searchBookAll(); } dataGridView1.DataSource = dt; DataGridViewColumn column = dataGridView1.Columns[1]; column.Width = 200; DataGridViewColumn column1 = dataGridView1.Columns[4]; column1.Width = 160; DataGridViewColumn column2 = dataGridView1.Columns[5]; column2.Width = 180; }