执行时在 sql 上添加不必要的引号 - codeigniter

Question

在尝试执行 select 查询时，我遇到了一种情况，即在执行时向其注入了不必要的引号。我在 Codeigniter 工作。尝试 selects 记录前 4 个字符相同。代码是：

$calendar = $this->db->select("c.first_name as cfn, u.first_name as ufn", false)
        ->from("{$this->tables['contacts']} c")
        ->join("{$this->tables['users']} u", " SUBSTR( u.first_name , 1 , 4) = SUBSTR( c.first_name , 1 , 4) ", '')
        ->where(array('c.status' => 1, 'c.first_name !=' => ''))
        ->get()->result_array();

我收到一个错误：

FUNCTION dbname.SUBSTR does not exist. Check the 'Function Name Parsing 
and Resolution' section in the Reference Manual

SELECT c.first_name as cfn, u.first_name as ufn FROM (`contacts` c) 
JOIN `users` u ON `SUBSTR`( `u`.`first_name` , 1 , 4) = SUBSTR( c.first_name , 1 , 4) 
 WHERE `c`.`status` = 1 AND `c`.`first_name` != ''

`SUBSTR` 查询不令人兴奋（SUBSTR 的单引号）。

Answer 1

我曾经遇到过同样的问题，我使用

解决了它

str_replace('"','',$string);

Answer 2

就我而言，我必须通过以下方式解决此问题：

$calendar = $this->db->query("SELECT c.first_name as cfn, u.first_name as ufn 
FROM (`contacts` c) JOIN `users` u ON 
((SUBSTR(`u`.`first_name`, 1, 4)) = (SUBSTR(`c`.`first_name`, 1, 4))) 
WHERE `c`.`status` = 1 AND `c`.`first_name` != ''")->result_array();
print_r($calendar);

执行时在 sql 上添加不必要的引号 - codeigniter

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