concat在php代码中 [英] concat in php codeigniter

问题描述

请帮助我理解正确的连接语法。

我有一个名为的库表，其中包含：

  trans_id 
 trans_items items  - > item_id 
 trans_user employees  - > person_id 
 trans_date 
 trans_comment 
 trans_inventory 
  

，trans_items是items表中的外键，trans_user是employees表中的外键，employee id是people表的外键。

现在我想做什么

---

p> EDIT ............................................... 。
所以我使用这个代码只显示雇员的姓氏：

  $ this-> ; db-> select（'inventory。*，items.name，people.last_name'）; 
 $ this-> db-> from（'inventory'）; 
 $ this-> db-> join（'items'，'inventory.trans_items = items.item_id'，'left'）; 
 $ this-> db-> join（'people'，'inventory.trans_user = people.person_id'，'left'）; 
 $ this-> db-> where（'deleted'，0）; 
 $ this-> db-> order_by（'trans_date desc'）; 
  

使用型号代码：

  foreach（$ report_data as $ row）
 {
 $ tabular_data [] = array（$ row ['name']，$ row ['last_name']，$ row ['trans_date']，$ row ['trans_inventory']，$ row ['trans_comment']）; 
} 
  

但我需要它是名字和姓氏，

  $ this-> db-> select（'inventory。*，items.name，CONCAT（people.first_name， ，people.last_name）as employee'）; 
 $ this-> db-> from（'inventory'）; 
 $ this-> db-> join（'items'，'inventory.trans_items = items.item_id'，'left'）; 
 $ this-> db-> join（'people'，'inventory.trans_user = people.person_id'，'left'）; 
 $ this-> db-> where（'deleted'，0）; 
 $ this-> db-> order_by（'trans_date desc'）; 
  

使用型号代码：

  foreach（$ report_data as $ row）
 {
 $ tabular_data [] = array（$ row ['name']，$ row ['employee']，$ row ['trans_date']，$ row ['trans_inventory']，$ row ['trans_comment']）; 
} 
  

如果我使用concat函数，请帮助。

解决方案

您的选择必须是这样的（$ this-中的第二个参数 - > db-> select part'，FALSE））：

  $ this-> db-> select（'inventory。*，items.name ，CONCAT（people.first_name，，people.last_name）as employee'，FALSE）; 
 $ this-> db-> from（'inventory'）; 
 $ this-> db-> join（'items'，'inventory.trans_items = items.item_id'，'left'）; 
 $ this-> db-> join（'people'，'inventory.trans_user = people.person_id'，'left'）; 
 $ this-> db-> where（'deleted'，0）; 
 $ this-> db-> order_by（'trans_date desc'）; 
 

从Codeigniter手册报价：

如果将其设置为FALSE，CodeIgniter
将不会尝试保护您的字段或
表格名称与反引号。这是
有用的，如果你需要一个复合选择
语句。




Please help me to understand proper join syntax.

I have table named inventory which has:

trans_id    
trans_items items -> item_id         
trans_user  employees -> person_id           
trans_date                   
trans_comment                
trans_inventory     

As you can see above, trans_items is a foreign key in items table, and trans_user is a foreign key in employees table and employee id is foreign key to people table.

Now what I want to do is to display in HTML the inventory table, but instead of displaying the employee id, I want the employee NAME to be displayed.

---

EDIT................................................ so i was enable to display only the last name of the employee with this code:

$this->db->select('inventory.*, items.name ,people.last_name');
$this->db->from('inventory');
$this->db->join('items', 'inventory.trans_items = items.item_id' , 'left');
$this->db->join('people', 'inventory.trans_user = people.person_id' , 'left');
$this->db->where('deleted', 0);
$this->db->order_by('trans_date desc');

with the model code:

foreach($report_data as $row)
        {
            $tabular_data[] = array($row['name'], $row['last_name'],$row['trans_date'], $row['trans_inventory'], $row['trans_comment']);
        }

but i need it to be first name and last name so i did these:

$this->db->select('inventory.*, items.name ,CONCAT(people.first_name, " ",people.last_name) as employee');
$this->db->from('inventory');
$this->db->join('items', 'inventory.trans_items = items.item_id' , 'left');
$this->db->join('people', 'inventory.trans_user = people.person_id' , 'left');
$this->db->where('deleted', 0);
$this->db->order_by('trans_date desc');

with the model code:

foreach($report_data as $row)
        {
            $tabular_data[] = array($row['name'], $row['employee'],$row['trans_date'], $row['trans_inventory'], $row['trans_comment']);
        }

it would error if i would use concat function. please help.

解决方案

Your select must be like this (second parameter in $this->db->select('your select part', FALSE) ):

$this->db->select('inventory.*, items.name ,CONCAT(people.first_name, " ",people.last_name) as employee', FALSE);
$this->db->from('inventory');
$this->db->join('items', 'inventory.trans_items = items.item_id' , 'left');
$this->db->join('people', 'inventory.trans_user = people.person_id' , 'left');
$this->db->where('deleted', 0);
$this->db->order_by('trans_date desc');

Quote from Codeigniter manual:

If you set it to FALSE, CodeIgniter will not try to protect your field or table names with backticks. This is useful if you need a compound select statement.

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