Php 从多个表中删除
因此,我尝试从多个表中删除(在本场景6中)。我尝试使用内部联接在一个查询中删除所有行,但无法使其工作 以下是我讨厌的作品:Php 从多个表中删除,php,mysql,codeigniter,Php,Mysql,Codeigniter,因此,我尝试从多个表中删除(在本场景6中)。我尝试使用内部联接在一个查询中删除所有行,但无法使其工作 以下是我讨厌的作品: // Delete course and everything linked to it (topics, badges, dotpoints, questions & answers) $topic = $this->db->query("SELECT * FROM course_topics WHERE cour
// Delete course and everything linked to it (topics, badges, dotpoints, questions & answers)
$topic = $this->db->query("SELECT * FROM course_topics WHERE course_id = ".$row_id);
foreach ($topic->result() as $t)
{
$badge = $this->db->query("SELECT * FROM course_topic_badges WHERE topic_id = ".$t->id);
foreach ($badge->result() as $b)
{
$dotpoint = $this->db->query("SELECT * FROM course_topic_dotpoints WHERE badge_id = ".$row_id);
foreach ($dotpoint->result() as $d)
{
$question = $this->db->query("SELECT * FROM quiz_questions WHERE dotpoint_id = ".$d->id);
foreach ($question->result() as $q)
{
$answer = $this->db->query("SELECT * FROM quiz_answers WHERE question_id = ".$q->id);
foreach ($answer as $a)
{
$this->db->query("DELETE FROM quiz_answers WHERE question_id = ".$q->id);
}
$this->db->query("DELETE FROM quiz_questions WHERE dotpoint_id = ".$d->id);
}
$this->db->query("DELETE FROM course_topic_dotpoints WHERE badge_id = ".$b->id);
}
$query = $this->db->query("DELETE FROM course_topic_badges WHERE topic_id = ".$t->id);
}
$query = $this->db->query("DELETE FROM course_topics WHERE course_id = ".$row_id);
}
$query = $this->db->query("DELETE FROM courses WHERE id = ".$row_id);
我如何简化这一点?您可以简化这一点:
$answer = $this->db->query("SELECT * FROM quiz_answers WHERE question_id = ".$q->id);
foreach ($answer as $a)
{
$this->db->query("DELETE FROM quiz_answers WHERE question_id = ".$q->id);
}
简单地
$this->db->query(“从问答题答案中删除,其中问题id=”.$q->id)
另一个选项(如果您有权限)是设置外键和“ON DELETE CASCADE”
否则,在不了解数据库结构的情况下,将很难重新获得更多。您可以使用子选择,但仍然需要一些级联
另一种选择是更改数据库结构,使其包含基于多个字段的主键(例如,课程主题点为“主题id、徽章id、点id”)然后你可以一次删除更多,但这可能需要一点修改。我为自己创建了一个函数,可以从多个表中删除
you need to SET FOREIGN_KEY_CHECKS = 0;
you can read more dev.mysql.com/doc/en/innodb-foreign-key-constraints.html
SET @BACKUP_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS;
SET @@FOREIGN_KEY_CHECKS=0;
-- Do stuff here
SET @@FOREIGN_KEY_CHECKS=@BACKUP_FOREIGN_KEY_CHECKS;
SET @BACKUP_FOREIGN_KEY_CHECKS=NULL;
给你
function delete_multiple_rows($table , $condition , $join_condition)
{
$table_count = count($table);
$join_count = count($join_condition) + 1;
if($table_count == $join_count)
{
if(count($condition)>0)
{
$delete_query = 'DELETE '. implode(' , ',$table) .' FROM '.$table[0];
$counter = 1;
foreach($join_condition as $key => $value)
{
$delete_query .= ' LEFT JOIN ' . $table[$counter] . ' ON ' . $key . ' = ' . $value;
$counter++;
}
$condition_counter = 1;
foreach($condition as $key => $value)
{
if($condition_counter > 1)
{
$delete_query .= ' AND ';
}else{
$delete_query .= ' WHERE ';
}
$delete_query .= $key . ' = ' . $value;
$condition_counter++;
}
$delete_query;
$this->db->query($delete_query);
}else{
echo 'This query requires at least 1 where condition.';
}
}else{
$table_count = count($table) - 1;
echo 'At least ' . $table_count . ' join conditions must be provided.';
}
}
如何使用
这些是控制器方法参数
$table = array('table1','table2','table3');
$condition = array('id'=>1,'2nd_condition'=>'blah');
$join_condition = array(
'table1.column' => 'table2.column',
'table1.column' => 'table3.column'
);
这非常有效您不需要发送查询,而应该在mysql数据库中设置一些触发器 分隔符$
在删除某些表之前创建触发器名称
每行开始 从一些其他表格中删除,其中一些id=NEW.id
结束$ 将其放入PHPMYADMIN中的SQL中,它将创建一个名为trigger_Name的触发器(其实并不重要) 每次在某个表上执行delete函数时,它都会使用您拥有的id删除某个其他表中的行
阅读了解更多信息。您能用英语解释一下“删除”是如何相互关联的吗?否则,如果它们不相关,那么单独的“delete”语句是最好的选择。一些带有级联删除的外键关系将在这里真正帮助您。我将如何确切地更改数据库结构以包含主键?请阅读此处:这可以很好地解释。哇。这让我大开眼界。非常感谢!哇!谢谢我会调查的@不客气,我要说的是,你可以用扳机连锁反应。如果表a的触发器影响表b,表b的触发器影响表c。发送到表a的查询可能会影响表b和c。谢谢你的提醒。