STRUCT_ELEMENT
描述
返回 struct 数据列内的某一 field
语法
STRUCT_ELEMENT( <struct>, `<filed_location>/<filed_name>`)
参数
| 参数 | 说明 |
|---|---|
<struct> | 输入的struct列，如果是null，则返回null |
<filed_location> | field的位置，起始位置从1开始，仅支持常量 |
<filed_name> | field的名字，仅支持常量 |
返回值
返回指定的 field 列，类型为任意类型
举例
select struct_element(named_struct('f1', 1, 'f2', 'a'), 'f2'),struct_element(named_struct('f1', 1, 'f2', 'a'), 1);
+--------------------------------------------------------+-----------------------------------------------------+
| struct_element(named_struct('f1', 1, 'f2', 'a'), 'f2') | struct_element(named_struct('f1', 1, 'f2', 'a'), 1) |
+--------------------------------------------------------+-----------------------------------------------------+
| a | 1 |
+--------------------------------------------------------+-----------------------------------------------------+
select struct_col, struct_element(struct_col, 'f1') from test_struct;
+-------------------------------------------------+-------------------------------------+
| struct_col | struct_element(`struct_col `, 'f1') |
+-------------------------------------------------+-------------------------------------+
| {1, 2, 3, 4, 5} | 1 |
| {1, 1000, 10000000, 100000000000, 100000000000} | 1 |
| {5, 4, 3, 2, 1} | 5 |
| NULL | NULL |
| {1, NULL, 3, NULL, 5} | 1 |
+-------------------------------------------------+-------------------------------------+
