如何计算具有相同列数据的行数并显示到表中？

Question

我有2个表格，'部门'和'文件'。

表department

| doc_id |  dept_name  | 
---------------------------------- 
|  1 | Information Technology| 
|  2 | Software Development | 
|  3 | Human Resource  | 
|  4 | Accounting   | 
|  5 | Support    | 

表document

| doc_id | doc_name | author | description | department    | 
---------------------------------------------------------------------------- 
|  1 | Maps  | User1 | sample  | Information Technology | 
|  2 | Audits  | User3 | sample  | Software Development | 
|  3 | Image  | User1 | sample  | Information Technology | 
|  4 | Papers  | User4 | sample  | Human Resource   | 
|  5 | Print Screen| User1 | sample  | Software Development | 
|  6 | Transaction | User3 | sample  | Accounting    | 
|  7 | Graph  | User1 | sample  | Support    | 
|  8 | Excel  | User1 | sample  | Information Technology | 

现在，我想有两列显示表：部门和total_doc。

输出：

|  department  |total_doc| 
----------------------------------- 
| Information Technology| 3  | 
| Software Development | 2  | 
| Human Resource  | 1  | 
| Accounting   | 1  | 
| Support    | 1  | 

我想要显示的部门内的总文档并以升序排列。

这是我的查询。（不知道）

SELECT department, count(doc_name) as 'total_doc' FROM tbl_document GROUP BY doc_name

我使用MVC模式的笨。

$this->db->select("department, count(doc_name) as 'total_doc'"); 
$this->db->from('document'); 
$this->db->group_by('doc_name'); 

此外，我怎样才能在表中显示这个？喜欢在HTML中使用foreach？

Answer 1

您需要按department进行分组，而不是doc_name。

$this->db->select("department, count(doc_name) as 'total_doc'"); 
$this->db->from('document'); 
$this->db->group_by('department'); 
$result = $this->db->get()->result(); 

希望这会帮助你。

foreach ($result as $row) 
{ 
    echo $row->department."----".$row->total_doc; 
} 

Answer 2

需要每个部门一行。 IN SQL单词：你想按分组。

select department, count(*) as total_doc from document group by department; 

（顺便说一句：请不要使用单引号列别名）

Answer 3

在这里你去

SELECT dept_name,COUNT(td.department) FROM department d 
LEFT JOIN tdocument td ON td.`department`=d.`dept_name` 
GROUP BY td.`department` ORDER BY COUNT(td.`department`) DESC;