Question

我正在寻找薪水低于平均工资的员工人数。

我对蜂巢和挣扎有点陌生，有人可以解释我的陈述有什么问题并请我帮忙吗？

我的陈述-

SELECT COUNT(*) FROM(SELECT wage, AVG(wage) AS avgWage FROM emp_wages) WHERE wage < avgWage;

错误-

ParseException line 1:82 cannot recognize input near 'where' 'wage' '<' in subquery source

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Answer 1

语法错误。派生表应为别名。

(on "<KeyPress-Left>" (setf dx -1))
(on "<KeyPress-Right>" (setf dx 1))
(on "<KeyRelease-Right>" (setf dx 0))
(on "<KeyRelease-Left>" (setf dx 0))

明智的查询，需要进行更改。

SELECT COUNT(*) 
FROM (SELECT wage, AVG(wage) AS avgWage FROM emp_wages group by wage)  t --alias needed here
WHERE wage < avgWage;

Answer 2

问题是AVG是聚合函数。如果要映射一对多关系，则需要使用交叉联接功能：

select 
  count(*), avg(v1.wage),
  sum(case when v.wage < v2.avgwage then 1 else 0 end) below_average
from 
emp_wages v cross join (select avg(wage) as avgwage from emp_wages) as v2

Answer 3

SELECT COUNT(*) 
FROM (SELECT wage, AVG(wage) AS avgWage FROM emp_wages group by wage)avg --group by needed
WHERE wage < avgWage;

Answer 4

正确的查询应为：

select count(*) where wage <(select avg(wage) from emp_wages);

由于工资和avgWage在子查询中，因此出现解析错误。

运行Hive查询时获取ParseException

4 个答案: