split_part
description
Syntax
VARCHAR split_part(VARCHAR content, VARCHAR delimiter, INT field)
根据分割符拆分字符串, 返回指定的分割部分(从一或负一开始计数)。field字段支持负数，代表从右往左倒着截取并取数。
delimiter 和 field 参数需要是常量, 不支持变量。
example
mysql> select split_part("hello world", " ", 1);
+----------------------------------+
| split_part('hello world', ' ', 1) |
+----------------------------------+
| hello |
+----------------------------------+
mysql> select split_part("hello world", " ", 2);
+----------------------------------+
| split_part('hello world', ' ', 2) |
+----------------------------------+
| world |
+----------------------------------+
mysql> select split_part("2019年7月8号", "月", 1);
+-----------------------------------------+
| split_part('2019年7月8号', '月', 1) |
+-----------------------------------------+
| 2019年7 |
+-----------------------------------------+
mysql> select split_part("abca", "a", 1);
+----------------------------+
| split_part('abca', 'a', 1) |
+----------------------------+
| |
+----------------------------+
mysql> select split_part("prefix_string", "_", -1);
+--------------------------------------+
| split_part('prefix_string', '_', -1) |
+--------------------------------------+
| string |
+--------------------------------------+
mysql> select split_part("prefix_string", "_", -2);
+--------------------------------------+
| split_part('prefix_string', '_', -2) |
+--------------------------------------+
| prefix |
+--------------------------------------+
mysql> select split_part("abc##123###234", "##", -1);
+----------------------------------------+
| split_part('abc##123###234', '##', -1) |
+----------------------------------------+
| 234 |
+----------------------------------------+
mysql> select split_part("abc##123###234", "##", -2);
+----------------------------------------+
| split_part('abc##123###234', '##', -2) |
+----------------------------------------+
| 123# |
+----------------------------------------+keywords
SPLIT_PART,SPLIT,PART