减去不同表中的2列 [英] Subtract 2 Columns from different tables

问题描述

我正在尝试建立一个查询，其中减去了来自不同表的2列.这是我尝试过的:

I'm trying to build a query where 2 columns from different tables get subtracted. This is what I tried:

DB::connection('lab_inv')->where('tab2'.'Amount_Run', '=', 'tab1'.'Amount')->selectraw('tab1.Amount - tab2.Amount_Run');

第一个表的值'Amount'对于每个id都是唯一的，第二个表由外键绑定到第一个表的id，并且参数'Amount_Run'随ID的不同而不同.金额=金额–金额运行.知道我在做什么错了.

The first table has the value ‘Amount’ which is unique for each id, the second table is bound by a foreign key to the id of the first table and has the parameter ‘Amount_Run’ which is also different depending on the id. Amount = Amount – Amount_run. Any Idea what I’m doing wrong.

推荐答案

如果我正确理解了您的问题，那么简单的联接然后减去就可以解决问题:

If i understood your question correctly, a simple join and then subtract would do the trick:

DB::connection('lab_inv')
    ->table('tab1')
    ->join('tab2', 'tab1.id', 'tab2.tab1_id') // replace this with the actual foreign key 
    ->selectraw('tab1.Amount - tab2.Amount_Run AS amount')
    ->get(); 

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