将employees表的所有员工的last_name和first_name拼接起来作为name,中间以一个空格区分
create table employees ( emp_no int(11) not null,
birth_date date not null,
first_name varchar(14) not null,
last_name varchar(16) not null,
gender char(1) not null,
hire_date date not null,
primary key (emp_no));
mysql、sql server、oracle等支持concat方法,
sqlite数据库只支持用连接符号”||”来连接字符串
select last_name||" "||first_name as name from employees