How should I check if resultset is empty or null using datastax cassandra driver for java

Question

How should I check for an empty resultset using datastax java cassandra driver?

Suppose I'm executing the following query "SELECT * FROM my_table WHERE mykey=something"

there is a great chance that the query will not be matched. The following code does not work:

if (rs != null) 
   rs.one().getString("some_column");

score 20 · Accepted Answer · edited Apr 06 '15 at 14:47

20

You were pretty close, the correct solution is:

Row r = rs.one();
if (r != null)
    r.getString("some_column");

The driver will always return a result set, whether or not there were any returned results. The documentation for one() states that if no rows were returned rs.one() returns null.

You can also use getAvailableWithoutFetching() which returns the number of rows in the result set without fetching more rows. Since pageSize has to be >= 1, you can be assured if there are is at least 1 row this will always return a value greater than 0.

edited Apr 06 '15 at 14:47

notanormie

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answered Apr 06 '15 at 13:19

Andy Tolbert

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Why is this better than using `rs.ìsExhausted`? – Martin Schröder Jul 13 '16 at 09:52

score 2 · Answer 2 · answered Apr 13 '16 at 00:02

2

You can also check the value of rs.isExhausted() in order to determine whether or not there is additional data in the result set...

answered Apr 13 '16 at 00:02

Darwin Airola

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How should I check if resultset is empty or null using datastax cassandra driver for java

2 Answers2