Android SQLite Query - Getting latest 10 records

Question

I have a database saved in my Android application and want to retrieve the last 10 messages inserted into the DB.

When I use:

Select * from tblmessag         


        

Answer 1

If your table contains a column with primary key autoincrement (some "row_id" for example) then you just need single select with DESC order by this column

Raw request looks like

select * from table_name order by row_id DESC limit 10

Android implementation is

private Cursor queryLastEvents() {
    return getDatabase().query("table_name", null, null, null, null, null, "row_id DESC", "10");
}

Answer 2

select * from
(select * from table_name order by yourfield ASC limit 10)
order by yourfield DESC;

You cannot have better solutions than this.

Answer 3

on large databases, the ORDER BY DESC statement really might slow down the system, e.g. raspberry pi. A nice approach to avoid ORDER BY is the OFFSET command. And you even keep the stored order:

SELECT * FROM mytable LIMIT 10 OFFSET (SELECT COUNT(*) FROM mytable)-10;

see: http://www.sqlite.org/lang_select.html

check out your performance with:

.timer ON