数据库查询时如何检测结果集是否为空

[fangzhaoguo]

数据库查询时如何检测结果集是否为空

try
			{
				con=DriverManager.getConnection("jdbc:MySQL://127.0.0.1:3306/Phone_Contacts", "root","fzg125009");
				if(radio_name.isSelected())
				{
					pre=con.prepareStatement("SELECT DISTINCT * FROM Contact WHERE name Like '"+field_name.getText()+"%'");
				}
				else if(radio_phone.isSelected())
				{
					pre=con.prepareStatement("SELECT DISTINCT * FROM Contact WHERE mobile Like '"+field_phone.getText()+"%'");
				}
				rs=pre.executeQuery();
				row=new CachedRowSetImpl();
				row.populate(rs);	
				if(row.wasNull())//这个不能被执行，所以这样检测不可以
				{
					text.append("Sorry,无此记录!\n");
				}
				con.close();
				while(row.next())
				{
					text.append(row.getString(1)+"\t");
					text.append(row.getString(2)+"\n");
				}
			}
			catch (SQLException error)
			{
				System.out.println("error!");
			}

谢谢大家

[风尘中国]

检测结果为空可以这样判断
if(rs==null){
System.out.println("查询结果为空");
text.append("Sorry,无此记录!\n");
}

[fangzhaoguo]

能这样用吗??
我没试过
不过字符串比较中这个都不可用==的

[fangzhaoguo]

[Quote=引用 1 楼 ioe_gaoyong 的回复:]

检测结果为空可以这样判断
if(rs==null){
System.out.println("查询结果为空");
text.append("Sorry,无此记录!\n");
}
[/Quote]
试了一下,不可以

[baillluu]

while(row.next())
{
text.append(row.getString(1)+"\t");
text.append(row.getString(2)+"\n");
}
row.close();
pre.close();
con.close();
if(text.toString().equals("")
{
text.append("Sorry,无此记录!\n");

}

[fangzhaoguo]

[Quote=引用 4 楼 baillluu 的回复:]

while(row.next())
{
text.append(row.getString(1)+"\t");
text.append(row.getString(2)+"\n");
}
row.close();
pre.close();
con.close();
if(text.toString().equals("")
{
……
[/Quote]
我有一个更好的方法

表示自己解决了

try
{
con=DriverManager.getConnection("jdbc:MySQL://127.0.0.1:3306/Phone_Contacts", "root","00000");
if(radio_name.isSelected())
{
pre=con.prepareStatement("SELECT DISTINCT * FROM Contact WHERE name Like '"+field_name.getText()+"%'");
}
else if(radio_phone.isSelected())
{
pre=con.prepareStatement("SELECT DISTINCT * FROM Contact WHERE mobile Like '"+field_phone.getText()+"%'");
}
rs=pre.executeQuery();
row=new CachedRowSetImpl();
row.populate(rs);
con.close();
if(!row.next())//这儿
{
text.append("Sorry,无此记录!\n");
}
else
{
row.beforeFirst();
while(row.next())
{
text.append(row.getString(1)+"\t");
text.append(row.getString(2)+"\n");
}
}
}
catch (SQLException error)
{
System.out.println("error!");
}

[fangzhaoguo]

[Quote=引用 4 楼 baillluu 的回复:]

while(row.next())
{
text.append(row.getString(1)+"\t");
text.append(row.getString(2)+"\n");
}
row.close();
pre.close();
con.close();
if(text.toString().equals("")
{
……
[/Quote]

不过你的也很不错，谢谢