获取复杂连接 codeigniter 4 的查询生成器

问题描述

我学习 codeigniter4 没多久。假设我有这 3 个表，员工、工作历史和部门

employee
id_employee | name |
1           | John |
2           | Mark |

working_history
id_history | id_employee | id_department | Year |
1          | 1           | 98            | 2010 |
2          | 1           | 99            | 2015 |
3          | 1           | 97            | 2020 |
4          | 2           | 99            | 2010 |
5          | 2           | 98            | 2017 |

department
id_department | department_name |
97            | Finance         |
98            | marketing       |
99            | production      |

我想使用 Codeigniter4 的查询构建器连接所有表。所以我可以得到这个结果。

id_employee | name | id_history | id_department | department_name | Year |
1           | John | 3          | 97            | Finance         | 2020 |
2           | Mark | 5          | 98            | Marketing       | 2017 |

这是使用 MysqL 的代码。

SELECT 
  e.id_employee,e.name,hist.id_history,hist.id_department,hist.year,dept.name_department
FROM
  employee e
LEFT OUTER JOIN (
       SELECT w.*
       FROM working_history w
       WHERE w.year = (
           SELECT year FROM working_history
           WHERE id_employee = w.id_employee
           ORDER BY year DESC
           LIMIT 1
       ) 
) as hist 
  ON hist.id_employee = e.id_employee
LEFT OUTER JOIN department as dept ON
  hist.id_department = dept.id_department

有人可以向我解释如何将这些 sql 代码转换为 codeigniter4 查询生成器吗？

解决方法

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