how to join four table to display specific data
我在加入表格时遇到了一些麻烦。我有四张桌子
"设备"表
1 2 3 4 | equipment_id equipment_name ----------- -------------- 1 Motor Cycle 2 Private Car |
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这是我的项目表
1 2 3 4 | project_id project_name ---------- ------------ 1 xyz trading 2 abc private ltd |
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这是出租桌
1 2 3 4 5 | rental_id project_id equipment_id Rental_date --------------------------------------------------------- 1 2 1 12/10/2018 2 2 2 15/09/2018 3 1 2 20/10/2018 |
这是删除表
1 2 3 4 5 6 | remove_id project_id equipment_id removal_date --------------------------------------------------------- 1 2 1 null 2 2 2 14/10/18 these are my table, now i want to display data of single equipment (eg: equipment no 2) in which project this equipment ran, when was the rental date and when was the removal date from a project. |
我想这样显示..(使用 Codeigniter)
设备2日志
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1 2 3 4 |
控制器传递给模型
1 | $data['eqipment_details']=$this->Equipment_model->getLog($equipment_id); |
请帮我查询
不得不猜测你的表名是什么，但你应该能够从中调整：
1 2 3 4 5 6 7 8 9 10 11 12 | SELECT (@cnt := @cnt + 1) AS SN, PROJECT.project_name AS Project Name, RENTAL.Rental_date AS Rental date, REMOVAL.removal_date AS Removal date FROM rental_table RENTAL LEFT JOIN project_table PROJECT ON (RENTAL.project_id = PROJECT.id) LEFT JOIN equipment_table EQUIPMENT ON (RENTAL.equipment_id = EQUIPMENT.id) LEFT JOIN removal_table REMOVAL ON (PROJECT.id = REMOVAL.project_id AND PROJECT.equipment_id = REMOVAL.equipment_id) WHERE EQUIPMENT.id = 2; |
我强烈建议与您的命名约定保持一致，您将骆驼大小写和标题大小写与下划线混合。