Храню данные в 2-х таблицах.
loans и installments
пример:
loan_id = в обеих таблицах
amount и status в таблие loans
date, principal, interest в installments
мне надо вытащить все записи в вот такую структуру, т.е 1 или несколько записей из таблицы installments относятся к одной записи из таблицы loans.

Подскажите как , голова не варит совсем !?
Здесь 2 записи в таблице loan, и 3 записи в таблице instalments.

[
  {
		"loan_id": "foo",
		"amount": 150,
		"status": "issued",
		"instalments": [{
			"date": "2016-07-15",
			"principal": 50.12,
			"interest": 0.08
		}, {
			"date": "2016-07-16",
			"principal": 30,
			"interest": 0.08
		}]
	},

	{
		"loan_id": "bar",
		"amount": 150,
		"status": "issued",
		"instalments": [{
			"date": "2016-07-15",
			"principal": 50.12,
			"interest": 0.08
		}]
	}
]

запрос из бд у меня обычный inner join, что в итоге получаю:

$array = array (

    array (
      'loan_id' => 'foo',
		'amount' => 120.00,
		'status' => 'requested',
		'principal' => 70.00,
		'interest' => 0.80,
		'date' => '2016-07-15'
    ),

    array (
      'loan_id' => 'bar',
		'amount' => 150.00,
		'status' => 'requested',
		'principal' => 30.00,
		'interest' => 0.80,
		'date' => '2016-07-16'
    ),

    array (
      'loan_id' => 'foo',
		'amount' => 150.00,
		'status' => 'requested',
		'principal' => 60.00,
		'interest' => 0.80,
		'date' => '2016-07-17'
    ),

    array (
      'loan_id' => 'baz',
		'amount' => 150.00,
		'status' => 'requested',
		'principal' => 25.00,
		'interest' => 0.80,
		'date' => '2016-07-18'
    ),

    array (
      'loan_id' => 'bar',
		'amount' => 150.00,
		'status' => 'requested',
		'principal' => 20.00,
		'interest' => 0.80,
		'date' => '2016-07-19'
    ),

    array (
      'loan_id' => 'hez',
		'amount' => 135.00,
		'status' => 'requested',
		'principal' => 20.00,
		'interest' => 0.80,
		'date' => '2016-07-20'
    ),

    array (
      'loan_id' => 'bar',
		'amount' => 150.00,
		'status' => 'requested',
		'principal' => 30.00,
		'interest' => 0.80,
		'date' => '2016-07-17'
    ),
);



function getLoans($dataArray) {

	$allLoans = [];
	foreach ($dataArray as $key => $val) {
		$currentLoan = [];
		$currentLoan['amount'] = $val['amount'];
		$currentLoan['status'] = $val['status'];
		$currentLoan['loan_id'] = $val['loan_id'];

		
		// find keys for this loan_id
		$thisLoanKeys = getLoanKeys($dataArray, $val['loan_id']);	
		
		// dostat date,principal,interest u vsex massivov po zadannqm klju4am
		$thisLoanInstalments = getThisLoanInstalments($dataArray, $thisLoanKeys);
		
		$currentLoan['instalments'] = $thisLoanInstalments;
		
		// sohranaem etot loan v $allLoans
		$allLoans[] = $currentLoan;
		
		
		// udalit massivq po etim klju4am
		
	
		// pereindeksirovat
		
		// vqzvat etu ze funkciju libo proverjat loan_id est li on uze v massive $allLoans
		
	}
	
	return $allLoans;
}

function getLoanKeys($array, $loanId){
	$keys = [];
	for($i=0; $i< count($array); $i++) {
		if(array_keys($array[$i], $loanId)) {
			$keys[] = $i;
		}
	}
	return [$loanId => $keys]; 
}


$allLoanIds = getLoanKeys($array, 'foo');


function getThisLoanInstalments($array, $allLoanIds) {
	foreach($allLoanIds as $k => $v)
	{
		$thisInstalment = [];
		foreach($v as $kkv){
			$loanInstalments['principal'] = $array[$kkv]['principal'];
			$loanInstalments['interest'] = $array[$kkv]['interest'];
			$loanInstalments['date'] = $array[$kkv]['date'];
			
			$thisInstalment[] = $loanInstalments;
		}
	}
	return $thisInstalment;
}



print_r(getLoans($array));