当 Hive 中不存在其他帐户时选择一个帐户

Question

我想在 Hive 中不存在其他 account_type 时选择帐户

我用Account_type = 'Second'过滤记录，但所有记录都来了

Select Account_ID, Account_type
From Account
Where Account_type = 'Second'

我的预期结果是：

Account_ID  Account_type

102         Second

实际结果是

Account_ID  Account_type

101         Second 
102         Second

Answer 1

如果Account_ID 存在一些account_type，则使用解析函数计算标志。

例如这个解析函数

max(case when Account_type='First'  then 1 else 0 end) over(partition by account_id) first_exists_flag

对于数据集中的所有 account_id=101 记录和 0 将是 1。希望你明白了。

当 First 不存在时选择 Second account_type：

with account as (
    select a.*, 
              max(case when Account_type='First'  then 1 else 0 end) over(partition by account_id) first_exists_flag,
              max(case when Account_type='Second' then 1 else 0 end) over(partition by account_id) second_exists_flag
              --you can add more such flags
          from Account a
)

select account_id, account_type
  from account a
where a.account_type='Second' and first_exists_flag=0;

当 First 和 Second 不存在时选择 Third account_type：

with account as (
    select a.*, 
              max(case when Account_type='First'  then 1 else 0 end) over(partition by account_id) first_exists_flag,
              max(case when Account_type='Second' then 1 else 0 end) over(partition by account_id) second_exists_flag
              --you can add more such flags
          from Account a
)

select account_id, account_type
  from account a
where a.account_type='Third' and first_exists_flag=0 and second_exists_flag=0;

您也可以在存在第三个帐户类型以外的其他帐户时计算标志：

max(case when Account_type <> 'Third'  then 1 else 0 end) over(partition by account_id) other_account_exist_flag

并使用other_account_exist_flag=0过滤