Hive嵌套的select语句

Question

我正在尝试在Hive中执行嵌套的select语句 -

select col1, (select COUNT(*) as cnt from table2) , col2 from table1;

当我在上面运行查询时，我遇到了异常 -

FAILED: ParseException line 1:8 cannot recognize input near 'select' 'COUNT' '(' in expression specification

我还尝试将选择计数（*）分配给hivevar并在查询中使用它。但是，我仍然遇到同样的问题。

set hivevar:cnt=select COUNT(*) as cnt from table2;
select col1, ${hivevar:cnt} , col2 from table1;

Answer 1

您可以在主表中使用WITH子句和CROSS JOIN。

WITH t AS (SELECT COUNT (*) AS ct FROM table2)
SELECT s.col1, t.ct, s.col2
  FROM table1 s CROSS JOIN t