如何在 Hive SQL 中实现与 OUTER UNION CORR 类似的结果？

Question

我正在尝试通过组合多个 table 来创建 table，但我需要在我的输出 table 中获取所有列。

Create table output_table
Select cl1, cl2, cl3, cl4
From table1
Union all
Select cl1, cl2, cl3, cl5
From table2
Union all
Select cl1, cl2, cl3, cl6
From table3
Union all
Select cl1, cl2, cl3, cl7
From table4

在这种情况下，我的输出 table 应该包含所有列。

请问有什么办法可以得到吗

Answer 1

我会在 Hive 中尝试这个（我想所有的列都是字符串，如果不是的话你可以放另一个值，例如如果字段是 int 你可以放 0 而不是 ''，或者你也可以放 null，最终结果相同)

CREATE TABLE output_table
ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
STORED AS TEXTFILE
AS
SELECT cl1, cl2, cl3, cl4, '' AS cl5, '' AS cl6, '' AS cl7
FROM table1
UNION ALL
SELECT '' AS cl1, '' AS cl2, '' AS cl3, '' AS cl4, cl5, '' AS cl6, '' AS cl7
FROM table2
UNION ALL
SELECT '' AS cl1, '' AS cl2, '' AS cl3, '' AS cl4, '' AS cl5, cl6, '' AS cl7
FROM table3
UNION ALL
SELECT '' AS cl1, '' AS cl2, '' AS cl3, '' AS cl4, '' AS cl5, '' AS cl6, cl7
FROM table4;

然后你可以清理这个 table 如下创建另一个 table 作为最终 table

CREATE TABLE final_table
ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
STORED AS TEXTFILE
AS
SELECT t.cl1, t1.cl2,t2.cl3,t3.cl4,t4.cl5,t5.cl6,t6.cl7
FROM (SELECT cl1 FROM output_table WHERE cl1 <> '') AS t,
     (SELECT cl2 FROM output_table WHERE cl2 <> '') AS t1,
     (SELECT cl3 FROM output_table WHERE cl3 <> '') AS t2,
     (SELECT cl4 FROM output_table WHERE cl4 <> '') AS t3,
     (SELECT cl5 FROM output_table WHERE cl5 <> '') AS t4,
     (SELECT cl6 FROM output_table WHERE cl6 <> '') AS t5,
     (SELECT cl7 FROM output_table WHERE cl7 <> '') AS t6;

如何在 Hive SQL 中实现与 OUTER UNION CORR 类似的结果？

How to achieve a similar result as OUTER UNION CORR in Hive SQL?

union

sas

union-all