Row to Column
Row to Column
Used in conjunction with generator functions such as EXPLODE
, will generate a virtual table containing one or more rows. LATERAL VIEW
applies rows to each raw output row.
Grammarβ
LATERAL VIEW generator_function ( expression [, ...] ) table_identifier AS column_identifier [, ...]
Parametersβ
generator_function
Generator functions (EXPLODE, EXPLODE_SPLIT, etc.).
table_identifier
Alias for
generator_function
.column_identifier
List column alias
generator_function
, which can be used to output rows. The number of column identifiers must match the number of columns returned by the generator function.
Exampleβ
CREATE TABLE `person` (
`id` int(11) NULL,
`name` text NULL,
`age` int(11) NULL,
`class` int(11) NULL,
`address` text NULL
) ENGINE=OLAP
UNIQUE KEY(`id`)
COMMENT 'OLAP'
DISTRIBUTED BY HASH(`id`) BUCKETS 1
PROPERTIES (
"replication_allocation" = "tag.location.default: 1",
"in_memory" = "false",
"storage_format" = "V2",
"disable_auto_compaction" = "false"
);
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');
mysql> SELECT * FROM person
-> LATERAL VIEW EXPLODE(ARRAY(30, 60)) tableName AS c_age;
+------+------+------+-------+----------+-------+
| id | name | age | class | address | c_age |
+------+------+------+-------+----------+-------+
| 100 | John | 30 | 1 | Street 1 | 30 |
| 100 | John | 30 | 1 | Street 1 | 60 |
| 200 | Mary | NULL | 1 | Street 2 | 30 |
| 200 | Mary | NULL | 1 | Street 2 | 60 |
| 300 | Mike | 80 | 3 | Street 3 | 30 |
| 300 | Mike | 80 | 3 | Street 3 | 60 |
| 400 | Dan | 50 | 4 | Street 4 | 30 |
| 400 | Dan | 50 | 4 | Street 4 | 60 |
+------+------+------+-------+----------+-------+
8 rows in set (0.12 sec)