在presto中，一个选项使用 sequence() 以及横向连接以生成行：

select t.id, x.value
from mytable t
cross join lateral unnest(sequence(1, t.freq)) as x(value)
order by t.id, x.value

好问题-一种方法是使用整数表-如果您确定重复次数不会超过（比如）128次，您可以按如下方式创建整数表：

CREATE TABLE nums(i INT PRIMARY KEY);
INSERT INTO nums VALUES (1);
INSERT INTO nums SELECT 1+i FROM nums;
INSERT INTO nums SELECT 2+i FROM nums;
INSERT INTO nums SELECT 4+i FROM nums;
INSERT INTO nums SELECT 8+i FROM nums;
INSERT INTO nums SELECT 16+i FROM nums;
INSERT INTO nums SELECT 32+i FROM nums;
INSERT INTO nums SELECT 64+i FROM nums;

现在您可以使用该表：

SELECT id, i AS value
 FROM input JOIN nums ON i BETWEEN 1 AND Freq

我会像gmb显示的那样用侧边。但是，在sql server中，可以通过另一种方式执行，例如：

with tally as 
(
  select top(select max(v) from myTable)
  ROW_NUMBER() OVER (ORDER BY t1.Object_ID) AS N
            FROM Master.sys.All_Columns t1
            CROSS JOIN Master.sys.All_Columns t2
)
select m.id, t.N
from tally t
cross join myTable m 
where t.N <= m.v
order by m.id, t.N;

dbfiddle演示