我如何在 codeigniter 模型中编写简单的 mysql 查询

Posted 2023-02-24

【中文标题】我如何在 codeigniter 模型中编写简单的 mysql 查询

【英文标题】：How i write simple mysql query in codeigniter model

【发布时间】：2021-08-18 19:45:44

【问题描述】：

SELECT DISTINCT 
  SUBSTRING_INDEX(SUBSTRING_INDEX(process_disposition.sub_dispo, ',', numbers.n), ',', -1) name
FROM
  (SELECT 1 n UNION ALL SELECT 2
   UNION ALL SELECT 3 UNION ALL SELECT 4) numbers INNER JOIN process_disposition
    ON CHAR_LENGTH(process_disposition.sub_dispo)
     -CHAR_LENGTH(REPLACE(process_disposition.sub_dispo, ',', ''))>=numbers.n-1
   

【问题讨论】：

我想在 Codeigniter 3 框架的模型中写这个

【参考方案1】：

你可以这样写

$query = $this->db->query("
                       SELECT DISTINCT SUBSTRING_INDEX
(SUBSTRING_INDEX(process_disposition.sub_dispo, ',', numbers.n), ',', -1)name FROM 
(SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4)numbers
INNER JOIN process_disposition ON CHAR_LENGTH(process_disposition.sub_dispo)
-CHAR_LENGTH(REPLACE(process_disposition.sub_dispo, ',', ''))>=numbers.n-1"
);

if ($query->num_rows() > 0) 
return $query->result();
 else 
return false;

【参考方案2】：

应该这样做。

$this->db->select("DISTINCT SUBSTRING_INDEX(SUBSTRING_INDEX(process_disposition.sub_dispo, ',', numbers.n), ',', -1) name");
$this->db->from("(SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4) numbers")
$this->db->join("process_disposition", "CHAR_LENGTH(process_disposition.sub_dispo)-CHAR_LENGTH(REPLACE(process_disposition.sub_dispo, ',', ''))>=numbers.n-1", "INNER");
$result = $this->db->get();

【讨论】：

当我使用这个不需要的空间时，它会自动在查询中查看 echo $this->db->last_query();这给了我

SELECT DISTINCT SUBSTRING_INDEX(SUBSTRING_INDEX(process_disposition.sub_dispo, ', ', numbers.n), ', ', -1) sub_dispo FROM (SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4) numbers INNER JOIN process_disposition ON CHAR_LENGTH(process_disposition.sub_dispo)-CHAR_LENGTH(REPLACE(process_disposition.sub_dispo, ',', ''))>=numbers.n-1