sql - 如何在 SQL 中将子查询添加为列

Question

如何在我的 SQL 脚本中添加子查询作为列？

例如

Select emp_no, name,gender ,
    (select department_name from departments where employees.emp_no = departments.emp_no)
from employees

PS:我用的是oracle 8

Answer 1

left join 是最佳实践，性能应该更快:

Select e.emp_no, e.name, e.gender , d.department_name
from employees e left join departments d on e.emp_no = d.emp_no;