my sqlite cursor returns empty result for a query

Question

I have a small function for checking to see if a records already exists in my sqlite database. There is data in the database that should match the query, i have verified this by opening up the database.But i get an empty result.

Below is the function, it takes in a parameter and uses that as the search parameter. i have also verified that the parameter is correct.

public boolean checkParent(String email)
{
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res = null;

    try
    {
        res = db.rawQuery("SELECT * FROM parents WHERE email = ' " + email + " ' ",null);
        res.close();
    }
    catch (Exception ex)
    {
        Log.e("Error checking parent", ex.toString());
    }

    if(res == null)
    {
        return true;
    }
    else
    {
        return false;
    }
}

Remove the spaces arond before and after `email` or even better used Pepared statements. No email in your DB starts and ends with a space I guess — juergen d, Sep 10 '16 at 11:44
use `SELECT * FROM parents WHERE email = ?` and pass `saelectionArgs` to `rawQuery` method — pskink, Sep 10 '16 at 11:46
You are closing cursor and then accessing the cursor. will it work? — Nikhil, Sep 10 '16 at 11:48

score 1 · Answer 1 · edited Sep 10 '16 at 11:52

1

Right way to pass argument in rawQuery method.

db.rawQuery("SELECT * FROM parents WHERE email = ?",new String[]{email});

edited Sep 10 '16 at 11:52

brahmy adigopula

617
3
15

answered Sep 10 '16 at 11:50

Yogesh Lakhotia

888
1
13
26

i still get android.database.sqlite.SQLiteCursor@2a39dbba as the result of the query – lagfvu Sep 10 '16 at 12:05
How to read data from cursor http://stackoverflow.com/questions/2810615/how-to-retrieve-data-from-cursor-class Check this answer it will help. – Yogesh Lakhotia Sep 10 '16 at 12:09
I am tried your answer ,still the same issue .The cursor return as empty . – Ganesan J Jun 16 '22 at 10:11

score 1 · Answer 2 · answered Sep 10 '16 at 12:25

You are checking whether the cursor object res is null. This will never happen; rawQuery() always returns a cursor object.

You have to check whether the cursor is empty, i.e., whether the cursor actually contains any rows. To do this, call a method like moveToFirst() and check if it succeeds.

Or even better, use a helper function that does handle the cursor for you:

public boolean checkParent(String email)
{
    SQLiteDatabase db = this.getReadableDatabase();
    long count = DatabaseUtils.queryNumEntries(db,
            "parents", "email = ?", new String[]{ email });
    return count > 0;
}

my sqlite cursor returns empty result for a query

2 Answers2