例如，‘dt’是一个字符串，我将其转换为日期类型，然后我想将其用作WHERE子句中的条件，但失败了：

hive> select mid,  cast(to_date(from_unixtime(unix_timestamp(dt, 'yyyyMMdd'))) as date) from message_use_tags where date<2021-11-08 and date >2021-11-01 limit 100;
FAILED: SemanticException Line 0:-1 Invalid table alias or column reference 'date': (possible column names are: mid, type, content, dt)

我已经将‘DT’转换为‘Date’，然后如何在WHERE子句中使用它？

推荐答案

请尝试以下代码。有时自动转换对某些工具不起作用。最好转换并信任代码而不是工具。

select mid,   to_date(from_unixtime(unix_timestamp(dt, 'yyyyMMdd')))  dt_new --you dont have to cast to date. to_date will reove time part
from message_use_tags 
where 
to_date(from_unixtime(unix_timestamp(dt, 'yyyyMMdd'))) < to_date(from_unixtime(unix_timestamp('2021-11-08', 'yyyy-MM-dd')))  -- convert hardcode dates properly as well
and 
to_date(from_unixtime(unix_timestamp(dt, 'yyyyMMdd'))) > to_date(from_unixtime(unix_timestamp('2021-11-01', 'yyyy-MM-dd')))   -- convert hardcode dates properly as well
limit 100;

请注意，我假定dt列是yyyyMMdd格式的字符串日期。