我有两张表,一张称为报价单,另一张称为发票。我想检索所有没有发票的报价单。以下是我到目前为止的代码。我只能检索所有报价。如何修改此查询
$quotations = Quotation::lists('id', 'id');
mysql> describe quotations;
+--- ---- --------+------------------+------+-----+---------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+------------------+------+-----+---------------------+-----------------------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| customer_id | int(10) unsigned | NO | MUL | NULL | |
| employee_id | int(10) unsigned | NO | MUL | NULL | |
| exchange_rate | int(11) | NO | | 0 | |
| remark | varchar(255) | NO | | | |
| created_at | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| updated_at | timestamp | NO | | 0000-00-00 00:00:00 | |
+---------------+------------------+------+-----+---------------------+-----------------------------+
mysql> describe invoices;
+--------------+------------------+------+-----+---------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+------------------+------+-----+---------------------+-----------------------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| quotation_id | int(10) unsigned | NO | MUL | NULL | |
| employee_id | int(10) unsigned | NO | MUL | NULL | |
| amount | int(11) | NO | | 0 | |
| balance | int(11) | NO | | 0 | |
| created_at | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| updated_at | timestamp | NO | | 0000-00-00 00:00:00 | |
+--------------+------------------+------+-----+---------------------+-----------------------------+