laravel 拉拉维尔 5.2。数据库表 + 加入更新
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Laravel 5.2. DB table + Join with Update
提问by Misha Babich
I need update key in table catalog and I write query (mysql query is right):
我需要表目录中的更新键并编写查询（mysql 查询是正确的）：
```
update attributes a inner join catalog c on a.parent_id = c.id set a.key = c.left_key
```
and with Laravel DB:
```
DB::table('attributes as a')
->join(catalog as c', 'a.parent_id', '=', 'c.id')
->update([ 'a.key' => 'c.left_key' ]);
```
It's right query, but DB::table ... make all key in table catalog to 0.
I write
```
DB::statement('update attributes a inner join catalog c on a.parent_id = c.id set a.key = c.left_key;');
```
And it's work! But I don't understand why DB::table with join and update don't work
这是工作！但我不明白为什么 DB::table with join 和 update 不起作用
回答by Amit Gupta
You can try as:
您可以尝试如下：
DB::table('attributes as a')
->join('catalog as c', 'a.parent_id', '=', 'c.id')
->update([ 'a.key' => DB::raw("`c`.`left_key`") ]);
回答by Glenys Mitchell
Probably the number of characters in the two columns are not the same.
可能两列中的字符数不一样。
make sure that the two assemblies have the same formatting or size
确保两个程序集具有相同的格式或大小
