CI对数据库句的操作有时很方便有时却让人为难,例如括号的问题。括号的问题来自于处理and和or的优先级关系。
有时需要or高于and。$this->db->where()和$this->db->orwhere()要如何做到呢。
第一种:自己写sql语句。可是有时候已经写好的程序要这样改动很难。
第二种:自己写where语句,有可能会遇到这样的问题。
where()和orwhere()其实是雷同的函数。
手册中有这样一段:
$this->db->where();
本函数允许你使用四种方法中的一种来设置 WHERE 子句:
说明: 传递给本函数的所有值都会被自动转义,以便生成安全的查询。
简单的 key/value 方法: $this->db->where('name', $name);// 生成: WHERE name = 'Joe'
请注意等号已经为你添加。
如果你多次调用本函数,那么这些条件会被 AND 连接起来:
$this->db->where('name', $name);$this->db->where('title', $title);
$this->db->where('status', $status);
// WHERE name = 'Joe' AND title = 'boss' AND status = 'active' 自定义 key/value 方法:
你可以在第一个参数中包含一个运算符,以便控制比较:
$this->db->where('name !=', $name);$this->db->where('id
// 生成: WHERE name != 'Joe' AND id $name, 'title' => $title, 'status' => $status);
$this->db->where($array);
// 生成: WHERE name = 'Joe' AND title = 'boss' AND status = 'active'
使用这个方法时你也可以包含运算符:
$array = array('name !=' => $name, 'id $id, 'date >' => $date);$this->db->where($array); 自定义字符串:
你可以手动的编写子句:
$where = "name='Joe' AND status='boss' OR status='active'";$this->db->where($where);
$this->db->where() 接受可选的第三个参数。如果你将它设置为 FALSE, CodeIgniter 将不会为你那些包含反勾号的字段名或表名提供保护。
$this->db->where('MATCH (field) AGAINST ("value")', NULL, FALSE);
标红的地方很重要,第4所说的:
$where = "name='Joe' AND status='boss' OR status='active'";
$this->db->where($where);
其实是行不通的。where()会给语句加上``,然后说:
"`name='Joe' AND status='boss' OR status='active'`"sql语句有错。
第三种:
改源代码:
CI论坛里有这样一段:
... ...
给like数组加上括号即可。
修改system\database\DB_active_rec.php
约第1559行
PHP
if ( count ( $this -> ar_like ) > 0 )
{
if ( count ( $this -> ar_where ) > 0 )
{
$sql .= "nAND " ;
}
$sql .= implode ( "n" , $this -> ar_like ) ;
}
改为
PHP
if ( count ( $this -> ar_like ) > 0 )
{
if ( count ( $this -> ar_where ) > 0 )
{
$sql .= "nAND (" ;
}
$sql .= implode ( "n" , $this -> ar_like ) ;
if ( count ( $this -> ar_where ) > 0 )
{
$sql .= ")" ;
}
}
希望CI开发者尽快修补or_like无法内部形成括号的BUG
这个论坛很脑残,显示回车符\n会掉一个斜杠,懂PHP的自己加上。
源自:http://codeigniter.org.cn/forums/thread-1270-1-1.html
同理,可以对where修改,但是这种只是对where语句的开始和末尾加。
对于实际的需要,几种合起来用基本情况都能解决了。不知道是不是还有更好的。呵呵,那应该就是直接修复CI源代码内部形成括号的BUG了吧

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