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
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
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if(rs==null){
System.out.println("查询结果为空");
text.append("Sorry,无此记录!\n");
}
{
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"); }
{
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!");
}