WEBVTT 00:00:00.350 --> 00:00:01.331 Welcome back! 00:00:01.511 --> 00:00:03.175 Here's what we'll learn in this lesson. 00:00:03.355 --> 00:00:05.979 Filter and sort using relationship paths. 00:00:06.159 --> 00:00:11.535 We will select invoices by customer city, order by date, and combine conditions with 00:00:11.535 --> 00:00:12.239 parameters. 00:00:13.569 --> 00:00:15.276 Continue in the same console. 00:00:15.456 --> 00:00:19.061 We will use the customers and invoices we imported last time. 00:00:19.241 --> 00:00:24.511 If Python was closed, the download includes a script to rebuild that temporary dataset. 00:00:25.850 --> 00:00:27.727 Let's find invoices for Florence. 00:00:27.907 --> 00:00:29.635 Use the customer city in where. 00:00:29.815 --> 00:00:33.421 Colon city is a parameter: its value is passed separately. 00:00:33.601 --> 00:00:35.734 We only ask to return the invoice number. 00:00:37.150 --> 00:00:38.899 Let's sort invoices by city. 00:00:39.079 --> 00:00:40.978 Use the same path in order by. 00:00:41.158 --> 00:00:43.547 Without a direction, the order is ascending. 00:00:43.727 --> 00:00:45.861 Limit keeps the displayed result short. 00:00:47.250 --> 00:00:48.957 Let's show the newest rows first. 00:00:49.137 --> 00:00:51.974 From an invoice row, follow its invoice to the date. 00:00:52.154 --> 00:00:53.839 Add DESC for descending order. 00:00:54.019 --> 00:00:56.579 These three rows belong to the latest invoice. 00:00:57.950 --> 00:00:59.635 Now start from an invoice row. 00:00:59.815 --> 00:01:03.613 To reach the customer city, go through the invoice and then the customer. 00:01:04.943 --> 00:01:06.585 Let's find rows for Florence. 00:01:06.765 --> 00:01:08.835 The filter follows two relationships. 00:01:09.015 --> 00:01:12.236 The returned columns follow the product relation instead. 00:01:12.416 --> 00:01:15.317 A field used in a filter need not be selected. 00:01:16.700 --> 00:01:18.300 Let's combine the conditions. 00:01:18.480 --> 00:01:22.256 Keep Florence rows from October first, newest invoices first. 00:01:22.436 --> 00:01:24.164 City and date are parameters. 00:01:24.344 --> 00:01:27.053 Neither filtered field needs to appear in the result. 00:01:27.233 --> 00:01:30.241 The same paths work in columns, where, and order by. 00:01:31.571 --> 00:01:33.385 Let's close this read transaction. 00:01:33.565 --> 00:01:37.063 We only read the data; the imported records have not changed. 00:01:38.450 --> 00:01:39.943 Thanks for following along! 00:01:40.123 --> 00:01:43.409 Use relationship fields wherever the query needs them. 00:01:43.589 --> 00:01:48.410 Select only what you want to read, and add just the conditions and ordering you need.