How to select distinct values from one column in table?

Question

I am developing a restaurant menu app in Android. My app has one database table which has the following columns:

id (primary key)
category
item name

The category column shows the category of item such as veg, non veg, snacks etc. It has duplicate values and I want to select only distinct values from this column. I have tried the following but it is not working if anyone can provide a solution:

String query = "SELECT DISTINCT category FROM todo"; Cursor cursor = database.rawQuery(query,null); if (cursor != null) { cursor.moveToFirst(); } return cursor;

i am not getting any sqlite errors, but app stops running, debuger shows error source not found. Curently i am not using any logging in app — sagar
– sagar, Commented Sep 13, 2011 at 14:11
You should use logcat to debug your application. It will give us more information about your problem.. — Jeremy D
– Jeremy D, Commented Sep 13, 2011 at 14:34

Bashorings · Accepted Answer · 2012-06-21 11:34:49Z

You can also use this specific query-Method of the SQLiteDatabase class that takes a boolean value to determine whether you want distinct values or not:

public Cursor query (boolean distinct, String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)

Link to Android Reference

This way you don't have to use rawQuery at all.

Aliaksei Kliuchnikau · Accepted Answer · 2012-02-29 09:59:15Z

6

Try:

"SELECT DISTINCT category as _id, category FROM todo"

This worked for me in the same situation.

edited Feb 29, 2012 at 9:59

Aliaksei Kliuchnikau

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answered Feb 29, 2012 at 8:51

StarSight

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2 Comments

Greener Over a year ago

Could you explain what this means? Why do you need to replace "FROM todo" with "as _id, category FROM todo"?

Shawn Over a year ago

This answer should really include more details than it worked for me.

KiKo · Accepted Answer · 2014-04-07 13:40:06Z

This is how i make distinct, also to get categories

// Get Categories public Cursor getCategories() { Cursor c = db.rawQuery("SELECT DISTINCT " + KEY_ITEM_CAT + " as " + KEY_ITEM_ID + ", " + KEY_ITEM_CAT + " FROM " + ITEMS_TABLE_NAME, null); if (c != null) { c.moveToFirst(); } return c; }

Community · Accepted Answer · 2017-05-23 12:08:14Z

I was searching for the same question, and I found something which is direct to the solution in the most simplest way! Check out this answer:

https://stackoverflow.com/a/13879436/4072073

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