Check if data is exist in SQLite Android

Question

I use this function to get specific data from SQlite:

SearchRes getSresultByName(String name) {
    SQLiteDatabase db = this.getReadableDatabase();

    Cursor cursor = db.query(TABLE_WIKIRES, new String[] { KEY_ID,
            KEY_SNAME, KEY_SJSON }, KEY_SNAME + "=?",
            new String[] { name }, null, null, null, null);

    if (cursor != null)
        cursor.moveToFirst();

    SearchRes searchres = new SearchRes(Integer.parseInt(cursor.getString(0)),cursor.getString(1), cursor.getString(2));

    return searchres;
}

And it works just fine, I need to create similar function to test if value is exist in the table, so I tried this:

boolean checkIfExist(String name) {
    SQLiteDatabase db = this.getReadableDatabase();

    Cursor cursor = db.query(TABLE_WIKIRES, new String[] { KEY_ID,
            KEY_SNAME, KEY_SJSON }, KEY_SNAME + "=?",
            new String[] { name }, null, null, null, null);


    if (cursor == null)
        return false;

    else
        return true;

}

But I always get TRUE. Can you help me figure out what is the problem?

stackoverflow.com/questions/18868712/…

Selvin
– Selvin

2013-09-19 16:26:00 +00:00
Commented Sep 19, 2013 at 16:26 — Selvin
– Selvin, Commented Sep 19, 2013 at 16:26

tyczj · Accepted Answer · 2013-09-19 16:26:15Z

6

you should not be checking if cursor is null you should be checking if anything exists in the cursor

if(cursor.moveToFirst()){
    return true
}else{
    return false;
}

answered Sep 19, 2013 at 16:26

tyczj

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Comments

Praful Bhatnagar · Accepted Answer · 2013-09-19 16:25:57Z

3

You can try Cursor getCount() to check the number of rows in the result of the query.. Following is the sample code:

boolean checkIfExist(String name) {
    SQLiteDatabase db = this.getReadableDatabase();

    Cursor cursor = db.query(TABLE_WIKIRES, new String[] { KEY_ID,
            KEY_SNAME, KEY_SJSON }, KEY_SNAME + "=?",
            new String[] { name }, null, null, null, null);


    if (cursor.getCount() > 0)
        return true;

    else
        return false;

}

answer by @tyczj is also good..

answered Sep 19, 2013 at 16:25

Praful Bhatnagar

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4 Comments

tyczj Over a year ago

doing this is redundant because if there is a count > 0 then you have to call movetoFirst() anyway or else you will get an out of bounds error

Praful Bhatnagar Over a year ago

agree.. but the purpose of the method is not to read data but to check if data exists.. and as I mentioned in my answer.. both approaches are good..

ChrisD Over a year ago

As explained by Doug Currie, getCount() is potentially a very expensive operation. Therefore I'd suggest it be avoided unless you need to get the total count.

Noor Hossain Over a year ago

But, I checked for null in Cursor, but there were exceptions shown in catch block when cursor count is 0, but, after applying the above method now fine, thanks for the approach.

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