How to join three custom table in magento 2

Question

I want join from Table 1 -> Table 2 has id = custom_id

Then join from Table 2 -> Table 3 has Table2.id = Table3.id

And will get table1.id if eligible

My Table

Ex : Table 1 -> Table 2

Table1.id = Table2.custom_id => choose two field

Table 2.id = Table3.id => choose one field

And get data Table 1

Answer 1

Well I don't understand your question as much, but from the title of the question I could answer you that. You want to join 3 tables and choose 2 columns of table2, 1 column from table3

So here: Assume the $collection is the resource model collection of the table 1.

We have

        $collection->getSelect()
            ->joinLeft(
                ['table2' => $collection->getTable('table2')],
                'main_table.id = table2.custom_id',
                [
                    'table2_id' => 'table2.id',
                    'table2_custom_id' => 'table2.custom_id'
                ]
            )
            ->joinLeft(
                ['table3' => $collection->getTable('table3')],
                'table2.id = table3.id',
                [
                    'table3_custom_field' => 'table3.custom_field'
                ]
            );