题解 | #获取Employees中的first_name#

题目描述：获取Employees中的first_name，查询按照first_name最后两个字母，按照升序进行排列
解答：

方案1：采用right函数
SELECT first_name
FROM employees
ORDER BY RIGHT(first_name,2) ASC;
方案2：采用substr函数
SELECT first_name
FROM employees
ORDER BY RIGHT(first_name,2) ASC;

补充：

RIGHT函数：

RIGHT(str,len):Returns the rightmost len characters from the string str, or NULL if any argument is NULL(返回字符串str中右边长度为len的字符，若str为'null'则统一返回'NULL').

LEFT函数

LEFT(str,len):Returns the leftmost len characters from the string str, or NULL if any argument is NULL(返回字符串str中左边长度为len的字符，若str为'null'则统一返回'NULL').

substr函数

SUBSTR(str,pos):（从左到右）从str中第pos位开始截取

SELECT SUBSTRING('Quadratically',5);
        -> 'ratically'

SUBSTR(str FROM pos):等同于substr(str,pos)

SELECT SUBSTRING('foobarbar' FROM 4);
        -> 'barbar'

SUBSTR(str,pos,len):(从左到右)从字符串str中第POS位开始截取，截取长度位len

SELECT SUBSTRING('Quadratically',5,6);
        -> 'ratica'

SUBSTR(str FROM pos FOR len)：等同于substr(str,pos,len)

SELECT SUBSTRING('Sakila' FROM -4 FOR 2);
        -> 'ki'

详细参考：
https://dev.mysql.com/doc/refman/8.0/en/string-functions.html
https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_substr