Laravel Query Builder 中来自不同数据库的联合查询

Union queries from different databases in Laravel Query Builder(Laravel Query Builder 中来自不同数据库的联合查询)

问题描述

我在两个不同的数据库中有两个相似的表.两个表都有一个包含日期的列和一个包含电子邮件地址的列.虽然列名不一样.因此，我希望得到一个包含两个表中所有记录的结果.

I have two similar tables in two different databases. Both tables have a column with a date and one with email addresses. Though the column names are not the same. As result I want to have one result that contains all records from both tables.

所以我的第一步是:

$emails_1 = DB::connection('db1')->table('contacts_1')->select('mail_address AS email', 'date as created_at');
$emails_2 = DB::connection('db2')->table('contacts_2')->select('email', 'created_at');

所以现在我有两个结果，结果中的列名是相等的(email 和 created_at).

So now I have two results and the column names in the result are equal (email and created_at).

现在我想将结果合并在一起，所以我这样做了:

Now I want to merge the results together, so I do:

$all_emails = $emails_1->union($emails_2);

这是我得到错误的地方:

And this is where I get the error:

未找到基表或视图:1146 表 'db1.contacts_2' 不​​存在存在 (SQL: (select mail_address as email, date as created_atfrom contacts_1) union (select email, created_at fromcontacts_2))

Base table or view not found: 1146 Table 'db1.contacts_2' doesn't exist (SQL: (select mail_address as email, date as created_at from contacts_1) union (select email, created_at from contacts_2))

因此，查询生成器似乎与不同的表混淆了.

So it seems that query builder gets confused with the diferente tables.

有人帮忙吗?

推荐答案

你不能使用不同的连接，但你仍然可以明确地提供数据库名称:

You can't use different connections, but you still can do it providing the db name explicitly:

$q1 = DB::table('db1.contacts')
       // where(..) or anything you need here
       ->select('mail_address as email', 'date as created_at');

$q2 = DB::table('db2.contacts')
       // like above
       ->select('email', 'created_at');

$result = $q2->union($q1)->get();

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