No column name was specified for column xx
报错语句示例：
select * FROM (
select d.dept_name,count(1) from sys_dept d GROUP BY d.dept_name
) as temp
报错原因：
因为加了临时表（新表），所以要指出新表的每一列的列名，例子中应该为count(1)定义别名
正确写法：
select * FROM (
select d.dept_name,count(1) as count from sys_dept d GROUP BY d.dept_name
) as temp
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