第10章,计算字段。
P64
select concat (vend_name,'(',vend_country,')') from vendors order by vend_name; # 拼接,vend_name(vend_country) #
P65 使用别名
select concat(RTrim(vend_name),'(',RTrim(vend_country),'),') as vend_titile from vendors order by vend_name; #拼接vend_name,vend_country ,RTrim ()函数去掉右边所有空格。#