连接sql

Question

编写一个查询，将员工ID与员工姓名中的前3个字符连接起来。使用别名显示为official_mail并按升序排列结果。

我的代码：

select staff_id as official_mail
from Staff
order by official_mail;

如何写前3个字符？

Answer 1

对于MySQL / MSSQL

SELECT CONCAT(staff_id,SUBSTRING(staff_name,1,3)) AS official_mail
FROM Staff
ORDER BY official_mail;

现场演示

  

http://sqlfiddle.com/#!9/f9c13b/1