Summary

我目前正在使用"$search_field LIKE '$this->db->escape_like_str($search_string)%'";逃避动态创建的搜索查询。创建的 SQL 语句结果不会产生任何错误，也不会产生任何结果。下面是我正在做的事情的详细描述。

Details

我正在使用 jqGrid 及其搜索功能。当用户输入搜索词时，它会发布$filtersjson 对象到我的服务器。然后我解析它并创建一个 SQL 语句来获取请求的数据。

这是转义传入搜索数据的代码（这也是问题区域）：

$search_string_like = $this->CI->db->escape_like_str($search_string);
$operator['bw'] = "$search_field LIKE '$search_string_like%'"; //begins with

下面是生成的 SQL 语句：

SELECT *
FROM player_data_temp_table
WHERE first_name LIKE '\'zech\'%' AND last_name LIKE '\'camp\'%'
ORDER BY date_won desc
LIMIT 0 , 15

此查询不会引发任何错误，但也不起作用。当我直接在 phpmyadmin 中运行类似的查询时，我得到，MySQL returned an empty result set (i.e. zero rows).尽管我知道有结果可以找到。如果我只是删除反斜杠和单引号first_name LIKE '\'zech\'%'做到这一点first_name LIKE 'zech%'然后我得到预期的结果。我担心的是，这不再是正确的转义，对吧？

用于构建查询的代码

Summary

一个变量，$filters，有这样的数据{"groupOp":"AND","rules":[{"field":"first_name","op":"bw","data":"zech"}]}被传递到build_where_clause($filters). build_where_clause返回完整的$where语句，然后在模型中使用它来创建最终的 SQL 搜索语句。

jqgrid_lib.php

class jqgrid_lib 
{
private $CI;

public function __construct()
{
    $this->CI =& get_instance();
}

/**
 * Function takes a json string with search rules and turns it into an sql statement.
 *
 * To use this function make sure you set stringResult: true, see example below:
 *   $("#list").jqGrid('filterToolbar',{stringResult: true});
 * @param   json string     
 * @author zechdc
 */
public function build_where_clause($filters)
{
    $sql_fragments = array();

    $filters = json_decode($filters);
    $rules = $filters->rules;
    $group_op = $filters->groupOp;

    //loop through each rule and create an sql statement
    foreach($rules as $rule)
    {
        $temp_sql = $this->create_search_field($rule->field, $rule->data, $rule->op);
        array_push($sql_fragments, $temp_sql);
    }

    //combine all sql fragments with the group_operator
    $data['sql'] = implode(' ' . $group_op . ' ', $sql_fragments);

    return $data;
}

/**
 * Takes a field, string and search condition and turns it into a sql search statement
 *
 * To use this function make sure you set stringResult: true, see example below:
 *   $("#list").jqGrid('filterToolbar',{stringResult: true});
 * @param   json string 
 * @return  string  
 * @author  zechdc
 */
public function create_search_field($search_field, $search_string, $search_operator)
{   
    //$search_field = $this->CI->db->escape($search_field); //escaping the column breaks it.
    $search_string = $this->CI->db->escape($search_string);
    $search_string_like = $this->CI->db->escape_like_str($search_string);
    //$search_string_like = $search_string;

    $operator['eq'] = "$search_field=$search_string"; //equal to
    $operator['ne'] = "$search_field<>$search_string"; //not equal to
    $operator['lt'] = "$search_field < $search_string"; //less than
    $operator['le'] = "$search_field <= $search_string "; //less than or equal to
    $operator['gt'] = "$search_field > $search_string"; //less than
    $operator['ge'] = "$search_field >= $search_string "; //less than or equal to
    $operator['bw'] = "$search_field LIKE '$search_string_like%'"; //begins with
    $operator['bn'] = "$search_field NOT LIKE '$search_string_like%'"; //not begins with
    $operator['in'] = "$search_field IN ($search_string)"; //in
    $operator['ni'] = "$search_field NOT IN ($search_string)"; //not in
    $operator['ew'] = "$search_field LIKE '%$search_string_like'"; //ends with
    $operator['en'] = "$search_field NOT LIKE '%$search_string_like%'"; //not ends with
    $operator['cn'] = "$search_field LIKE '%$search_string_like%'"; //in
    $operator['nc'] = "$search_field NOT LIKE '%$search_string_like%'"; //not in
    $operator['nu'] = "$search_field IS NULL"; //is null
    $operator['nn'] = "$search_field IS NOT NULL"; //is not null

    if(isset($operator[$search_operator])) 
    {
        //set the sql search statement
        return $operator[$search_operator];
    } 
}
}

Model

/*
 * Gets all columns from table with limit and sort order set dynamically
 */
function get_specific($sidx, $sord, $start, $limit, $where = NULL)
{
    $result = FALSE;

    if($where)
    {
        $where = ' WHERE ' . $where;
    }

    // usually I dont do select all but since this whole table is temp and only holds the needed data
    // then just do select all.
    $sql = "SELECT *
            FROM player_data_temp_table
            $where
            ORDER BY $sidx $sord
            LIMIT $start , $limit"; 

    $q = $this->db->query($sql);

    if($this->db->affected_rows() > 0)
    {
        $result = $q->result();
    }

    return $result;
}

更新/回答：

看来我解决了这个问题。在模型中，我删除了手工制作的 $sql 语句并将其替换为

    if($where)
    {
        $this->db->where($where);
    }

    $this->db->order_by($sidx, $sord);
    $q = $this->db->get('player_data_temp_table', $limit, $start);

这似乎正确地转义了所有变量，包括 $where 语句中的列名。

Manual http://codeigniter.com/user_guide/database/queries.html:

$this->db->e​​scape_like_str() 当要在 LIKE 条件下使用字符串时，应使用此方法，以便字符串中的 LIKE 通配符（'%'、'_'）也能正确转义。

$search = '20% raise';
$sql = "SELECT id FROM table WHERE column LIKE '%".$this->db->escape_like_str($search)."%'";

所以你在最后两行代码中做得正确。

下面的代码对你有什么作用？

$search_string = 'zech';
$search_string_like = $this->CI->db->escape_like_str($search_string);
$operator['bw'] = "$search_field LIKE '$search_string_like%'";