Two further alternatives for improved expressiveness:

  q('select name from users where id = :userid', compact('userid'));

  q('select name from users where id = ?', [ $userid ]);

Recommend using single quotes for SQL (command) literals, rather than doublequotes. This helps with discouraging string interpolation (" ... WHERE col = $value "). This also helps very much with SQL quoting object names (tables, columns, indexes, etc) - SQL specifies doublequote (") as the quoting character; for example 'SELECT COUNT(users.id) AS "Number of users" FROM users', or 'CREATE VIEW "My daily report" AS SELECT SUM("count") FROM "some strange table" LEFT JOIN ...'.