aspose file tools*
The moose likes JDBC and the fly likes Check the result set Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login


Win a copy of Spring in Action this week in the Spring forum!
JavaRanch » Java Forums » Databases » JDBC
Bookmark "Check the result set" Watch "Check the result set" New topic
Author

Check the result set

Ikasari Widiyanto
Greenhorn

Joined: May 31, 2004
Posts: 29
Hi,

I want to know what is the difference between while(rs.next()) and if(rs.next())? I'm not sure about this but I think that while is for more than 1 data in the db while if is to check whether there is data or not inside db and can only retrieve 1 data.
so my question is:
if I have no data on 1 thing but I have 1 or more data on another 1 then how to check for that one.because in my program some still don't have data so this part, I always have java.lang.nullpointerexception. thanks...
Paul Sturrock
Bartender

Joined: Apr 14, 2004
Posts: 10336

The next() method of a ResultSet moves the cursor on to the next record, returning true if there is another record to move to and false if there is not. Typically since you don't usually know how many records are in a ResultSet you would access its contents in a loop, so:

is the typical way of dealing with ResultSets. I suppose you could use:

if you are sure there will always be 0 or 1 records. But it sounds like a dangerous assumption.


JavaRanch FAQ HowToAskQuestionsOnJavaRanch
G Raghavan
Greenhorn

Joined: Aug 21, 2000
Posts: 15
While you want to iterate through the entire ResultSet you have to use


There might be some instances where you want to just check if there are results in the ResultSet, so instead of iterating through the entire ResultSet we can use


G Raghavan
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Check the result set