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Android select statement returns no results via rawquery or query while using query directly works

I've spent the whole day so far trying to get a select query to execute viarawquery or query, but I've had no luck so far.
The select statement I want to run is as the following:
SELECT * FROM h_word WHERE category='GRE' AND DONE=0 ORDER BY RANDOM() LIMIT 1
category is a TEXT type column and DONE is an INTEGER type with the default value of 0.
While the query works fine when executed directly in SQLite, in android,it doesn't return any results.
I've tried the below with no luck (the method is located in a class extended from SQLiteAssetHelper which itself is a helper class originally extended from SQLiteOpenHelper originaly taken from here: https://github.com/jgilfelt/android-sqlite-asset-helper:
public Cursor getRandomWord() {
Cursor c;
SQLiteDatabase db = getWritableDatabase();
c=db.rawQuery(query, null);
String query = "SELECT * FROM h_word WHERE category='GRE' AND DONE='0'
ORDER BY RANDOM() LIMIT 1 ";
c=db.rawQuery(query, new String[] {});
c.moveToFirst();
db.close();
return c;
}
I also tested with GRE instead of 'GRE' and 0 instead of '0' but it made no difference.
did the following as well:
public Cursor getRandomWord() {
Cursor c;
SQLiteDatabase db = getReadableDatabase();
c=db.query(true, "h_word", new String[] {
"_id",
"word",
"english_meaning"
},
"category" + "=?" + " AND " +
"DONE" + "=?",
new String[]{"GRE" ,"0"},
null, null, "RANDOM() LIMIT 1" , null);
c.moveToFirst();
db.close();
return c;
}
but the cursor remains empty.
Any ideas what I might be doing wrong here?
Any help would be much appreciated.
PS: when running a simple select statement without a where clause it, works fine.

After another few hours of struggling, I figured it's a bug in android's SQLiteDatabase class.
I managed to solve the problem by changing the name of the "category" column to something else.
Seems like "category" is a key word in the android SQLiteDatabase code, and makes a query return nothing when written in where clauses on the android side.
Someone else also had this problem here:
Android rawquery with dynamic Where clause

Are android SQLite queries executed lazily?

I just encountered something strange. Say I have a table
_id | caption
1 | foo
and I execute the following query on it directly in SQLite:
select _id, (caption != "bar") as caption from the_table;
I get the (expected) output:
_id | caption
1 | 1
Executing this code however:
// This will execute the EXACT SAME query (checked via debugger)
Cursor affected = db.query(table, (String[]) projection.toArray(new String[0]), selection, selectionArgs, null, null, null);
// ############ UPDATE ROW 1 TO CAPTION=bar #######
int result = db.update(table, values, selection, selectionArgs);
affected.moveToPosition(-1);
while (affected.moveToNext()) {
long id = affected.getLong(0); // We made the _id column the first in the projection
for (int i = 1; i < affected.getColumnCount(); i++) {
Log.d("xyz", affected.getInt(i) + "");
}
}
gets me: "xyz 0" in LogCat.
Does the cursor execute the query lazily on the first cursor access?
It seems to work if I insert affected.getCount() right after the query.

Yes, there are leaky abstractions.
Query alone translates to a prepare call that compiles the SQL to a sqlite program (think bytecode). The program is not run.
To run a compiled sqlite program, one would use the step which either returns a result row, finihsed status code, or an error. In Android, you effectively run the program by calling one of the moveTo...() methods on the returned cursor.
Getting cursor count is not directly supported by the sqlite C API. Android implements it by running the query and storing the results in a "cursor window" buffer. The same buffer is used for accessing the cursor's data later.

Pointing second cursor to same database in sqlite on android, this a no no?

I have this function that is filling out a class based on data from several tables. I got the first cursor:
String query="SELECT * FROM SESSION where _id =" + mSessionID + ";";
Cursor c = dbAdapter.selectRecordsFromDB(query, null);
Session session=null;
c.moveToFirst();
This works great. Then a little lower I do this:
long galleryId = c.getInt(4);
long packageId = c.getInt(5);
long contractId = c.getInt(6);
String query2="SELECT * FROM PHOTOPACKAGES WHERE _id =" + packageId + ";";
Cursor p = dbAdapter.selectRecordsFromDB(query2, null);
and the p cursor always returns -1 for its count. I can go right into the sqlite in the adb and run the same query where packageId = 1 and it works great...so not sure why this is not working, i don't see any other errors...can you just not use two cursors on the same database? p.s. selectRecordsFromDB is a helper function:
public Cursor selectRecordsFromDB(String query, String[] selectionArgs) {
Cursor c = myDataBase.rawQuery(query, selectionArgs);
return myDataBase.rawQuery(query, selectionArgs);
}

To answer your actual question: Yes you can target the same DB with multiple cursors. I believe there is something else wrong with your code.
Also as Philip pointed out, creating Cursors is very costly and you do not want to make extras just because, and always close them when finished with them.

Your selectRecordsFromDB function looks pretty darned weird, but it will probably work after a fashion, because the first cursor that you create goes out of focus straight away. Leaking open cursors like that is not a good idea though.

Where clause in SQLite not working in android :(

I'm getting an annoying error when trying to query some data in SQLite.
Here is my code:
Cursor cursor= db.query(TABLE_IMAGES, new String[]{"_id"}, "name" +" = "+compareToThis, null, null, null, null);
I'm just returning the cursor as a string.
The error is saying:
no such column: compareToThis: while compiling.....the statement
My question is: why is SQLite setting the compareToThis attribute as a column when it's just a value?
How can I fix this?
Thanks in advance.

Cursor cursor= db.query(TABLE_IMAGES, new String[]{"_id"}, "name" +" = ?", new String[]{compareToThis}, null, null, null);
The selection must include placeholder for parameter, and the next argument should be the array of parameters.

The solution by Vladimir works, however if you are like me and wonder why your approach did not work initially when it should have, here is why:
It is because it expects an integer unless you used (single or double) quotation marks to indicate that it is a string.
For example, in MySql this would return no results:
SELECT * FROM clients WHERE firstName = Bob; -- This will not work.
However when you surround it with quotations, it will return a result because it identifies Bob as a String literal.
Select * FROM clients WHERE firstName = 'Bob'; -- Single quotes work.
Select * FROM clients WHERE firstName = "Bob"; -- Double quotes as well.
Therefore for it to work, you would have to surround your compareToString with single quotes, as Muhhammad mentioned within the comments.
Cursor cursor= db.query(TABLE_IMAGES, new String[]{"_id"}, "name" +'" = "+compareToThis+"'", null, null, null, null);

Using the LIMIT statement in a SQLite query

I have a query that selects rows in a ListView without having a limit. But now that I have implemented a SharedPreferences that the user can select how much rows will be displayed in the ListView, my SQLite query doesn't work. I'm passing the argument this way:
return wDb.query(TABELANOME, new String[] {IDTIT, TAREFATIT, SUMARIOTIT}, CONCLUIDOTIT + "=1", null, null, null, null, "LIMIT='" + limite + "'");

The equals (=) operator is not used with the LIMIT clause. Remove it.
Here's an example LIMIT query:
SELECT column FROM table ORDER BY somethingelse LIMIT 5, 10
Or:
SELECT column FROM table ORDER BY somethingelse LIMIT 10
In your case, the correct statement would be:
return wDb.query(TABELANOME, new String[] {IDTIT, TAREFATIT, SUMARIOTIT}, CONCLUIDOTIT + "=1", null, null, null, null, String.valueOf(limite));
Take a look here at the SQLite select syntax: http://www.sqlite.org/syntaxdiagrams.html#select-stmt
This image is rather useful: http://www.sqlite.org/images/syntax/select-stmt.gif

For anyone stumbling across this answer looking for a way to use a LIMIT clause with an OFFSET, I found out from this bug that Android uses the following regex to parse the limit clause of a query:
From <framework/base/core/java/android/database/sqlite/SQLiteQueryBuilder.java>
LIMIT clause is checked with following sLimitPattern.
private static final Pattern sLimitPattern = Pattern.compile("\\s*\\d+\\s*(,\\s*\\d+\\s*)?");
Note that the regex does accept the format offsetNumber,limitNumber even though it doesn't accept the OFFSET statement directly.

Due to this bug which also doesn't allow for negative limits
8,-1
I had to use this workaround
SQLiteQueryBuilder builder = new SQLiteQueryBuilder();
builder.setTables(table);
String query = builder.buildQuery(projection, selection, null, null, null, sortOrder, null);
query+=" LIMIT 8,-1";