题解 | #顾客登录名#

concat(s1,s2,s3...)字符连接

upper（s）转大写

substr(s,i,length),i为第i个字符，i>=1

select cust_id,cust_name, 
upper(concat(substr(cust_contact,1,2),substr(cust_city,1,3)))  
as user_login from Customers;