Question

我正在努力从数据库中删除但不是加入表，我选择了costume_id（主键）并尝试删除这种方式，但它似乎只从一个表而不是所有表中删除。我已经尝试在主键之前删除外键但这不起作用。我是否必须加入表格然后删除或以我的方式工作？

   $select =  $mysqli->query("SELECT * FROM costumes WHERE $q");
   while ($row = $select->fetch_assoc())
            $db_id = $row["costume_id"];

   $costume = $mysqli->query("DELETE FROM costumes WHERE costume_id='$db_id'");
   $costume_row = $costume->fetch_assoc();

   $history = $mysqli->query("DELETE FROM history WHERE history_id='$db_id'");
   $history_row = $history->fetch_assoc();

   $location = $mysqli->query("DELETE FROM location WHERE location_id='$db_id'");
   $location_row = $location->fetch_assoc();

   $state = $mysqli->query("DELETE FROM state WHERE state_id='$db_id'");
   $state_row = $state->fetch_assoc();

$ q是一个子流。在我的表中有：

costumes (
  costume_id varchar(10) primary key,
  name varchar(50), 
  is_seperate bool, 
  is_onepeice bool, 
  description text, 
  color varchar(25), 
  material varchar(50), 
  genre varchar(25), 
  gender char(1), 
  size varchar(5)
);
state (
  state_id varchar(10), 
  in_use bool, 
  fixed bool, 
  condition text, 
  foreign key (state_id) references costume(costume_id)
);
history (
  history_id varchar(10), 
  previous_user varchar(20), 
  profession varchar(20), 
  previous_play varchar(50), 
  date date, fixed_previous bool, 
  comments text, 
  foreign key (history_id) references costume (costume_id)
);
location (
  location_id varchar(10), 
  loc_no varchar(10) primary key, 
  room_no varchar(3), 
  foreign key (location_id) references costumes (costume_id)
);

我的删除新查询是：

 $delete = $mysqli->query("DELETE costumes,history,status,location FROM costumes join   history on costumes.costume_id = history.history_id join status on status.status_id join location on location.location_id where costume_id='$db_id'");

该查询给了我约束问题

Answer 1

您应该在delete语句中加入表。所以完成此查询然后尝试：

DELETE costumes, history
FROM costumes JOIN history ON costume.costume_id = history.costume_id
WHERE costume_id = '$db_id';

由于我不确切知道您的表的结构，因此您必须更正连接语法以匹配您通常加入它们的方式。如需进一步的帮助，请尝试编辑您的问题，并在2个表格中为我们提供所有字段名称。

Answer 2

我认为你应该使用外键的ON DELETE CASCADE属性。使用此功能，当您删除服装时，它也会删除历史记录表中的该客户。

Answer 3

试试这个::

DELETE from costumes where costumeid in 
(
Select temp_costume.id from
( Select costume_id as id from table....
) as temp_costume

选择然后从数据库中删除

3 个答案: