struct_element
struct_element
struct_element
description
返回struct数据列内的某一field
Syntax
struct_element(struct, n/s)
Arguments
struct - 输入的struct列，如果是null，则返回null
n - field的位置，起始位置从1开始，仅支持常量
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
mysql> select struct_element(named_struct('f1', 1, 'f2', 'a'), 'f2');
+--------------------------------------------------------+
| struct_element(named_struct('f1', 1, 'f2', 'a'), 'f2') |
+--------------------------------------------------------+
| a |
+--------------------------------------------------------+
1 row in set (0.03 sec)
mysql> select struct_element(named_struct('f1', 1, 'f2', 'a'), 1);
+-----------------------------------------------------+
| struct_element(named_struct('f1', 1, 'f2', 'a'), 1) |
+-----------------------------------------------------+
| 1 |
+-----------------------------------------------------+
1 row in set (0.02 sec)
mysql> 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 |
+-------------------------------------------------+-------------------------------------+
9 rows in set (0.01 sec)
keywords
STRUCT, ELEMENT, STRUCT_ELEMENT
