试试看这是否有效。
using (SqlCeCommand com = new SqlCeCommand("INSERT INTO TenOperations (EUR, Rate, BGN, Date) Values(@EUR1, @Rate1, @BGN1, @Date1),(@EUR2, @Rate2, @BGN2, @Date2)", connection))
{
com.Parameters.AddWithValue("@EUR1", textBox2.Text.ToString());
com.Parameters.AddWithValue("@Rate1", EURbuy);
com.Parameters.AddWithValue("@BGN1", textBox1.Text.ToString());
com.Parameters.AddWithValue("@Date1", Date2.Text.ToString());
com.Parameters.AddWithValue("@EUR2", textBox4.Text.ToString());
com.Parameters.AddWithValue("@Rate2", EURbuy);
com.Parameters.AddWithValue("@BGN2", textBox3.Text.ToString());
com.Parameters.AddWithValue("@Date2", Date4.Text.ToString());
com.ExecuteNonQuery();
}