TP7H272p

1CREATE TABLE
2IF NOT EXISTS test_tbl(
3    id INTEGER);
4INSERT INTO test_tbl
5VALUES (10),
6       (13),
7       (14),
8       (16),
9       (18),
10       (20);
11-------------------------------    
12SELECT * FROM test_tbl;
13
14-------------------------------    
15SELECT COALESCE(tmp.id, 20) AS classification_id
16FROM (
17       SELECT tt.id,
18              row_number() over(
19       ORDER BY tt.id) AS row_num
20       FROM test_tbl tt
21     ) tmp
22WHERE tmp.row_num =floor(random() * 10);