Issue with SQLite query in Android

Question

I have an SQLite database where I have a table named object_zone. This table has two columns, of type integer: object and zone.

If I copy the database onto my computer, and query it with:

SELECT object FROM object_zone WHERE zone = 791

it returns several rows.

However, on my Android phone, if I query it with:

Cursor cursor = database.query( "object_zone", new String[] {"object"}, "zone = ?", new String[] { Long.toString( zoneId )}, null, null, null);

Where zoneId = 791, the cursor contains 0 rows. How have I stuffed up the usage of the query function?

Dan Breslau · Accepted Answer · 2011-01-12 05:06:26Z

1

Did you call cursor.moveToFirst() on the returned cursor? Without having called that, cursor.getCount() may erroneously return 0 (or perhaps it's -1...)

I've been tripped up by this a few times...

answered Jan 12, 2011 at 5:06

Dan Breslau

11.5k2 gold badges37 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Ogre Over a year ago

The trouble is, I have a loop right after that query that iterates over the rows in the cursor, using cursor.moveToNext(), and the loop does not execute at all, (i'm using the boolean return as the loop condition, i.e. while( cursor.moveToNext() ). As far as I can tell, it's returning no rows. The weird part is that I use the same construct earlier in my code for a different query and it works fine, the only differences being that that query has no WHERE clause, and it's querying a different table.

Dan Breslau Over a year ago

@Ogre: Please add that code to the question. If you're only calling moveToNext(), and not starting by calling moveToFirst(), then I think the results are undefined. (I could be wrong about this, but I think the call to moveToNext() is needed.)

Pedro Fraca · Accepted Answer · 2011-01-12 08:37:13Z

0

Maybe the problem here is the casting to string. Can you try the rawQuery method with the same sql that you executes on your computer?

answered Jan 12, 2011 at 8:37

Pedro Fraca

1859 bronze badges

2 Comments

Ogre Over a year ago

Hmm, using rawQuery, I gave it "SELECT object FROM object_zone WHERE zone = " + Long.toString( zoneId ) as the first parameter, null as the second, and it's working now. Something weird is happening with the substitution of ? for the string array elements though.

Pedro Fraca Over a year ago

I think is related to the cast, try to use an int array.

Collectives™ on Stack Overflow

Issue with SQLite query in Android

2 Answers 2

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related