Netezza不支持相关查询

Question

我有以下SQL查询：

select * from table1 a where 
      a.ORD_EXEC_INST = 'M' and 
      a.evt_ts >= '2016-05-16' and 
      a.evt_ts < '2016-05-17' and
      a.prc = (select mid_pt_prc from table2 where evt_ts <= a.evt_ts order by evt_ts desc limit 1)

我收到以下错误：

This form of correlated query is not supported - consider rewriting

我不太清楚这意味着什么。有没有办法重新写这个来遵守Netezza？