LATERAL VIEW Clause 俗称「列转行」。
官方示例:
CREATE TABLE person (id INT, name STRING, age INT, class INT, address STRING);
INSERT INTO person VALUES
(100, 'John', 30, 1, 'Street 1'),
(200, 'Mary', NULL, 1, 'Street 2'),
(300, 'Mike', 80, 3, 'Street 3'),
(400, 'Dan', 50, 4, 'Street 4');
SELECT * FROM person
LATERAL VIEW EXPLODE(ARRAY(30, 60)) tableName AS c_age
LATERAL VIEW EXPLODE(ARRAY(40, 80)) AS d_age;
+------+-------+-------+--------+-----------+--------+--------+
| id | name | age | class | address | c_age | d_age |
+------+-------+-------+--------+-----------+--------+--------+
| 100 | John | 30 | 1 | Street 1 | 30 | 40 |
| 100 | John | 30 | 1 | Street 1 | 30 | 80 |
| 100 | John | 30 | 1 | Street 1 | 60 | 40 |
| 100 | John | 30 | 1 | Street 1 | 60 | 80 |
| 200 | Mary | NULL | 1 | Street 2 | 30 | 40 |
| 200 | Mary | NULL | 1 | Street 2 | 30 | 80 |
| 200 | Mary | NULL | 1 | Street 2 | 60 | 40 |
| 200 | Mary | NULL | 1 | Street 2 | 60 | 80 |
| 300 | Mike | 80 | 3 | Street 3 | 30 | 40 |
| 300 | Mike | 80 | 3 | Street 3 | 30 | 80 |
| 300 | Mike | 80 | 3 | Street 3 | 60 | 40 |
| 300 | Mike | 80 | 3 | Street 3 | 60 | 80 |
| 400 | Dan | 50 | 4 | Street 4 | 30 | 40 |
| 400 | Dan | 50 | 4 | Street 4 | 30 | 80 |
| 400 | Dan | 50 | 4 | Street 4 | 60 | 40 |
| 400 | Dan | 50 | 4 | Street 4 | 60 | 80 |
+------+-------+-------+--------+-----------+--------+--------+
可以认为是把数组变成几行,再去做 JOIN。