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This article mainly introduces how to use laravel hasManyThrough, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

In the first case, I call it a conduction correlation table (simple schema)

There are many users in the country, and users have many posts

Countries id-integer name-stringusers id-integer country_id-integer name-stringposts id-integer user_id-integer title-string

Query all posts in a country, how to achieve?

Countries is the table, posts is the target table to be exported, and users is the intermediate table

Return $this- > hasManyThrough ('App\ Post',' App\ User', 'country_id',' user_id')

In the second case, there is an intermediate table (pure intermediate table)

Exam_paper (examination paper table) idnameexam_paper_question (intermediate list of examination papers and questions) idexam_paper_idquestion_idexam_question (examination paper table) idname

We need to query question through exam_paper 's id

Return $this- > hasManyThrough ('exam_question',' exam_paper_question', 'exam_paper_id',' id','id','question_id') / Parameter 1 target table class name exam_question,// parameter 2 hub table class name exam_paper_question,// parameter 3 field name associated with the current table 'exam_paper_question.exam_paper_id',// parameter 4 field name associated with the hub table' exam_question.id',// parameter 5 field name associated with the hub table in the current table 'exam_paper.id' / / Parameter 6 the field name associated with the hub table and the target table is' exam_paper_question.question_id')

If you record the current table as A, the target table as B, and the intermediate table as CMagol 6 parameters (BMague CMagna CA BCMagol CB)

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