在Codeigniter 2.0中编写SQL查询 [英] Writing SQL Queries in Codeigniter 2.0

问题描述

我有以下功能，不工作，我有最难的时间试图找出来。我12岁，只是学习，请原谅我：

  function get_answer（）{
 $ answer = $ this - > db-> query（SELECT COUNT（questions）FROM possible_quest WHERE questions ='something'）; 
 
 return $ answer; 
} 
  

当我在phpmyadmin中运行以下SQL查询时，它返回预期结果

  SELECT COUNT（questions）FROM possible_quest WHERE questions ='something'
  

如何使用上面的函数在CodeIgniter中工作？

我得到的PHP错误是

遇到PHP错误

严重性：4096

消息：CI_DB_mysql_result类的对象不转换为字符串

解决方案

可能是：

  function get_answer（）
 {
 $ query = $ this-> db-> query（SELECT COUNT FROM possible_quest WHERE questions ='something'）; 
 
 $ count = $ query-> row（）; //返回第一行的对象
 return $ count-> count; 
 // OR 
 $ count = $ query-> row_array（）; // return a asociative array of the result 
 return $ count ['count'];另一件事：如果你想传递'som​​ething'作为一个变量，你可以将一个变量传递给另一个变量，例如：
} 
  

可以使用参数化查询，如

  $ sql =SELECT COUNT（questions）AS count FROM possible_quest WHERE questions =？ 
 $ query = $ this-> db-> query（$ sql，array（$ something））; 
  

这有利于自动转义你的变量，所以你不必担心sql注入。 / p>

I have the following function that does not work and I'm having the hardest time trying to figure it out. I'm 12 and just learning, so forgive me:

function get_answer() {
$answer = $this->db->query("SELECT COUNT(questions) FROM possible_quest WHERE questions='something'");              

return $answer;
}

When I run the following SQL query in phpmyadmin, it returns the expected result

SELECT COUNT(questions) FROM possible_quest WHERE questions='something'

How do I get this working in CodeIgniter using my function above?

The PHP error I get is

A PHP Error was encountered
Severity: 4096
Message: Object of class CI_DB_mysql_result could not be converted to string

解决方案

Could be:

function get_answer() 
{
$query = $this->db->query("SELECT COUNT(questions) AS count FROM possible_quest WHERE questions='something'");

$count =  $query->row(); // returns an object of the first row
return $count->count;
// OR
$count =  $query->row_array(); // returns an asociative array of the result
return $count['count'];
}

Another thing: if you want to pass 'something' as a variable, you can use parametrized query, like

 $sql = "SELECT COUNT(questions) AS count FROM possible_quest WHERE questions = ?";
 $query = $this->db->query($sql, array($something));

which has the benefit of escaping automatically your variable, so you don't worry about sql injections.

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