Question

C#comboBox如何让下拉菜单中有数据库的某列多种选项

数据库中booktype表，有三个字段，自增长的编号id，int类型；名称name，nvarchar（20）类型。

我的combobox数据如下：
private void book__Load(object sender, EventArgs e)
{
//打开数据库
string con = "Data Source=(local);Initial Catalog=LBOS;Integrated Security=True";
SqlConnection sqlcon = new SqlConnection(con);
sqlcon.Open();

string sql = "select bookTypeName from bookType";
SqlCommand b = new SqlCommand(sql, sqlcon);
SqlDataReader A = b.ExecuteReader();
while (A.Read())
{
comboBox1.Items.Add(A[1].ToString());
A.Close();
}
}
我这样写了combobox下拉就只有一个选项 其他的都看不到

Answer 1

private void book__Load(object sender, EventArgs e)
{
//打开数据库
string con = "Data Source=(local);Initial Catalog=LBOS;Integrated Security=True";
SqlConnection sqlcon = new SqlConnection(con);
sqlcon.Open();

string sql = "select bookTypeName from bookType";
SqlCommand b = new SqlCommand(sql, sqlcon);
SqlDataReader A = b.ExecuteReader();
while (A.Read())
{
comboBox1.Items.Add(A[1].ToString());
}
A.Close();
}

Answer 2

把A.Close();这一句删掉试试