CodeIgniter中的数据库错误处理问题

Question

I use CodeIgniter as my web application framework. I used a simple Try/Catch and I sent a sample value to test it, and it failed!

I know I can use $this->db->escape() function to solve my data problem but I just want to know: Why TRY/CATCH can not catch this error!

Controler code:

    $this->load->model('user_model');
    $result = $this->user_model->test_user("tes'ti");

Model code:

function test_user($username){
    try {
        $query_str = "SELECT * FROM tbl_user WHERE username = '".$username."'";
        $result = $this->db->query($query_str);
        return $result;

    } catch (Exception $e) {
        return;

    }
}

Output:

A Database Error Occurred

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ti'' at line 1

SELECT * FROM tbl_user WHERE username = 'tes'ti'

Let me know, where I made a mistake, if I did!

Answer 1

You need to throw an exception if there was some mysql error:

try {
    $query_str = "SELECT * FROM tbl_user WHERE username = '".$username."'";
    $result = $this->db->query($query_str);

    if (!$result)
    {
      throw new Exception('error in query');
      return false;
    }        

    return $result;

} catch (Exception $e) {
    return;
}