How to remove records if more than 20

[juvenalb]

The thing is, I need to delete if the records are more than 20 and only the old ones, that's the date. I found a SQL request somewhere.

DELETE tt
FROM 
  ( SELECT DISTINCT uid             --- these 3 lines can be replaced
    FROM tableX                     --- with:   UserTable AS du
  ) AS du                           --- a table that you probably have
JOIN
  tableX AS tt
ON  tt.uid = du.uid
AND tt.timestampColumn >
    ( SELECT timestampColumn AS ts
      FROM tableX
      WHERE uid = du.uid 
      ORDER BY ts ASC
      LIMIT 1 OFFSET 199
    )

But that's not clear. I can remove more than 20, but the problem is, two checks, and I'm in the SQLite newcomers, a pot in the head.

I have these poles:

private static final String TABLE_SEARCH = "search_table";
private static final String KEY_ID = "id";
private static final String KEY_DATE = "date";

How do I use the request above? And how do you redo db.delete?

[elysha]

DELETE FROM search_table
WHERE date NOT IN (
    SELECT date 
    FROM search_table 
    ORDER BY date desc 
    LIMIT 20
)

He was on his knee, there might be fingerprints, but that's the idea.
Internally, we choose everything that needs to be left, i.e. a top of 20 records on the date, and externally, we remove everything, except that we chose the inside.

Here's another option, this better one:

DELETE FROM search_table
WHERE id < SELECT id from (

SELECT id, date

FROM search_table

ORDER BY date desc

LIMIT 1 OFFSET 19

)