Pass a slice to a query

Pass a variable-length list to an IN predicate with kind: slice. The emitter binds the values and supplies the appropriate empty-list test.

Declare the list input

In a configured SQLite project, mark the placeholder as a slice:

-- sgl.query(HutsOnBeaches, many)
-- ?1 as sgl.param(beaches, kind: slice)
SELECT number, beach, colour, booked
FROM huts
WHERE beach IN (?1)
ORDER BY number;

Keep the placeholder as the list’s single item. For a list beside other scalar inputs, give each its own binding:

-- sgl.query(FreeHutsInColours, many)
-- ?1 as sgl.param(beach)
-- ?2 as sgl.param(colours, kind: slice)
SELECT number, colour
FROM huts
WHERE beach = ?1 AND colour IN (?2) AND booked = 0
ORDER BY number;

The schema gives the compared columns their types. This is an input-list directive, distinct from reading an array column.

Pass populated and empty lists

Run sgl generate and construct store.New(database). Pass the generated params struct:

	free, err := queries.FreeHutsInColours(ctx, store.FreeHutsInColoursParams{
		Beach:   "Polzeath",
		Colours: []string{"blue", "yellow"},
	})
	if err != nil {
		return fmt.Errorf("finding free huts: %w", err)
	}

An empty slice matches no row for IN and excludes no row for NOT IN. Include that case in the caller’s tests; the example exercises an empty beach list as well as populated ones.

Check expanded and empty lists

From the Seagull repository root, run the slice example:

cd examples/sqlite/010_slices
go test .

The example test provides its local inputs. See its caller for the exact Go API and its test for assertions and failure handling.

The complete example produces:

huts on [Polzeath Fistral]: [1 2 3 6]
huts on [Watergate]: [4 5]
huts on []: []
booking huts [1 3 4] booked 3
booking huts [3 5] booked 1
hut 2 at Polzeath is yellow and free

Let the emitter bind the list

With database/sql, values expand into bound placeholders at call time. pgx uses an array with ANY or ALL instead. ClickHouse takes an Array parameter directly and needs no kind: slice. A list exceeding the engine’s bind-variable limit returns ErrSglTooManyBindVariables before reaching the database.

See the directives reference for the complete contract. The example browser exposes other engine variants; use their actual SQL rather than changing only the dialect name.