我有两张桌子:
CREATE TABLE Student_registration (
id INT AUTO_INCREMENT PRIMARY KEY,
Name VARCHAR(255) NOT NULL,
Contact VARCHAR(255) NOT NULL,
regdatetime TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
CREATE TABLE timestamp_table (
id INT AUTO_INCREMENT PRIMARY KEY,
timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
执行此查询时:
select *
from Student_registration
LEFT JOIN (select count(*)
from Student_registration)
where RegDateTime > (select timestamp
from timestamp_table
where id= 1);
我收到此错误:
ERROR 1248 (42000): Every derived table must have its own alias
我该如何解决这个问题?
答案 0 :(得分:0)
您应该在此处添加别名(临时名称):
(select count(*) from Student_registration)
所以它会是这样的:
(select count(*) as total from Student_registration)
此处总计您可以用不同的名称命名。
使用JOIN时也可以使用 代替 。