struct_element

SinceVersion 2.0

struct_element

description

返回struct数据列内的某一field

Syntax

1. struct_element(struct, n/s)

Arguments

1. struct - 输入的struct列，如果是null，则返回null
2. n - field的位置，起始位置从1开始，仅支持常量
3. s - field的名字，仅支持常量

Returned value

返回指定的field列，类型为任意类型

notice

只支持在向量化引擎中使用。

example

1. mysql> select struct_element(named_struct('f1', 1, 'f2', 'a'), 'f2');
2. +--------------------------------------------------------+
3. | struct_element(named_struct('f1', 1, 'f2', 'a'), 'f2') |
4. +--------------------------------------------------------+
5. | a                                                      |
6. +--------------------------------------------------------+
7. 1 row in set (0.03 sec)

9. mysql> select struct_element(named_struct('f1', 1, 'f2', 'a'), 1);
10. +-----------------------------------------------------+
11. | struct_element(named_struct('f1', 1, 'f2', 'a'), 1) |
12. +-----------------------------------------------------+
13. |                                                   1 |
14. +-----------------------------------------------------+
15. 1 row in set (0.02 sec)

17. mysql> select struct_col, struct_element(struct_col, 'f1') from test_struct;
18. +-------------------------------------------------+-------------------------------------+
19. | struct_col                                      | struct_element(`struct_col `, 'f1') |
20. +-------------------------------------------------+-------------------------------------+
21. | {1, 2, 3, 4, 5}                                 |                                   1 |
22. | {1, 1000, 10000000, 100000000000, 100000000000} |                                   1 |
23. | {5, 4, 3, 2, 1}                                 |                                   5 |
24. | NULL                                            |                                NULL |
25. | {1, NULL, 3, NULL, 5}                           |                                   1 |
26. +-------------------------------------------------+-------------------------------------+
27. 9 rows in set (0.01 sec)

keywords

STRUCT, ELEMENT, STRUCT_ELEMENT