int number = 0; 
string connstr = @"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\lando\Desktop\UML Extension\MyPratices\WebServices\App_Data\Database1.mdf;Integrated Security=True;User Instance=True"; 
using (SqlConnection conn = new SqlConnection(connstr)) 
{ 
conn.Open(); 
string str = "select * from Test"; 
using (SqlCommand cmd = conn.CreateCommand()) 
{ 
cmd.CommandText = str; 
SqlDataReader dr = cmd.ExecuteReader(); 
while (dr.Read()) 
{ 
string name = dr["Name"].ToString(); 
DateTime dt = dr.GetDateTime(dr.GetOrdinal("InputDate")); 
<STRONG>if (dr["Name"] == null) { number += 1; } </STRONG> } 
} 
} 
if (number == 0) 
Label1.Text = "不存在Name為null的值"; 
else 
Label1.Text = "Name為空值的個數為:" + number; 
 
然后，在看看我數據里的數據： 

在我們的Test表里，有3個數據，而第三條數據的Name字段的值為空，剛剛開始，我理所當然的認為在Label里會