# Keep rows with chosen values

Shape / rows

A variant of [Filter rows](https://meridian.online/operations/filter-rows).

Keep or exclude the rows whose value is one of a picked list of values.

Page: <https://meridian.online/operations/filter-rows/keep-rows-with-chosen-values>

## Status

Runs as a SQL step.

arcform carries it as a `sql:` step today.

## The DuckDB step

keep or exclude rows whose value is one of a picked list

It reads the `orders` table the proofs share. Create it first:

```sql
CREATE TABLE orders AS SELECT * FROM (VALUES
  (1,  'Alice Ng',      'north', DATE '2026-01-03', 120.00, 'widget', 'a|b',   '{"channel":"web","items":[1,2]}'),
  (2,  'alice ng',      'north', DATE '2026-01-05',  80.50, 'gadget', 'b',     '{"channel":"shop","items":[3]}'),
  (3,  'Bob  Okafor',   'south', DATE '2026-01-05', 300.00, 'widget', 'a|c',   '{"channel":"web","items":[4,5,6]}'),
  (4,  'Carla Díaz',    'east',  DATE '2026-01-09',  NULL,  'gizmo',  NULL,    '{"channel":"web","items":[]}'),
  (5,  'Bob Okafor',    'south', DATE '2026-01-12',  45.25, 'gadget', 'c',     '{"channel":"phone","items":[7]}'),
  (6,  'Dev Patel',     'west',  DATE '2026-01-12', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (7,  'Carla Diaz',    'east',  DATE '2026-01-20',  99.99, 'gizmo',  'b|c',   '{"channel":"shop","items":[10]}'),
  (8,  'Dev Patel',     'west',  DATE '2026-02-02', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (9,  'Eve Larsen',    NULL,    DATE '2026-02-03',  15.00, 'gadget', NULL,    '{"channel":"web","items":[11]}'),
  (10, 'Alice Ng',      'north', DATE '2026-02-10', 220.00, 'gizmo',  'a|b|c', '{"channel":"phone","items":[12,13]}')
) t(order_id, customer, region, order_date, amount, product, tags, meta);
```

Then run the statement:

```sql
CREATE TEMP TABLE picked AS SELECT * FROM (VALUES ('north'), ('west')) t(region);
-- keep the picked values, from a literal list and from a table of picks
CREATE TEMP TABLE kept AS SELECT order_id FROM orders WHERE region IN ('north', 'west');
CREATE TEMP TABLE kept_from_table AS SELECT order_id FROM orders WHERE region IN (SELECT region FROM picked);
-- exclude them; NOT IN alone would drop the row whose region is missing, so keep it explicitly
CREATE TEMP TABLE excluded AS SELECT order_id FROM orders WHERE region IS NULL OR region NOT IN ('north', 'west');
SELECT list(order_id ORDER BY order_id) AS kept FROM kept;
SELECT list(order_id ORDER BY order_id) AS excluded FROM excluded;
SELECT CASE WHEN ((SELECT list(order_id ORDER BY order_id) FROM kept) = [1, 2, 6, 8, 10] AND (SELECT list(order_id ORDER BY order_id) FROM kept_from_table) = [1, 2, 6, 8, 10] AND (SELECT list(order_id ORDER BY order_id) FROM excluded) = [3, 4, 5, 7, 9]) THEN 'as expected' ELSE error('the picked regions were not orders 1, 2, 6, 8 and 10, or the others, with the order that has no region, were not 3, 4, 5, 7 and 9') END AS verdict;
```

It needs nothing installed beyond DuckDB itself.

## What other tools call it

Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3).

- EasyMorph: [`Filter`](https://help.easymorph.com/doku.php?id=transformations:selectionfilter) (read 2026-09-27)
- KNIME Analytics Platform: [`Nominal Value Row Filter`](https://api.hub.knime.com/nodes/*DBlot_cJykJ7wkzA?details=full) (read 2026-09-27)
- Tableau Prep: [`Exclude`](https://help.tableau.com/current/prep/en-us/prep_filter.htm) (read 2026-09-27)
- Tableau Prep: [`Keep Only`](https://help.tableau.com/current/prep/en-us/prep_filter.htm) (read 2026-09-27)
- Tableau Prep: [`Selected Values`](https://help.tableau.com/current/prep/en-us/prep_filter.htm) (read 2026-09-27)
- Trifacta: [`Filter in`](https://help.alteryx.com/aac/en/trifacta-classic/reference/transformation-reference.html) (read 2026-09-27)