Oracle_071_lesson_p8
嵌套子查询subquery单行子查询
select select_list
from table
where expr operator
(selectselect_listfrom table);
operator includes a comparison condition such as >, =, or IN
如：
select last_name,hire_date
from employees
where hire_date > (select hire_date from employees where last_name = 'Davies');
[可选] and> 如:
select A from table
group by C
having min(column)>(select ......);
当子查询有group by 时，其输出行数只能是1行；
多行子查询
IN , ANY, ALL
select employee_id,last_name,job_id,salary
from employees
where salary
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