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Introduction
Points
Linestrings
Polygons
Summary

## Instruction

Perfect! Next, let's get to know a couple functions that will be useful when we work with linestrings. The first two are ST_StartPoint(geometry) and ST_EndPoint(geometry). Take a look at how they're used:

SELECT
ST_AsText(ST_StartPoint(course)),
ST_AsText(ST_EndPoint(course))
FROM sf_selected_railways
WHERE id = 1;

In the query above, we show the start and end point of the railway with id = 1. Note that we used ST_AsText(...) and passed in ST_StartPoint(...) as its argument. That's because ST_StartPoint and ST_EndPoint return points in the internal PostGIS format, which is not very human-readable. Thus, we used ST_AsText(...) to convert it to WKT.

As you can tell, spatial functions can be nested, or put inside one another.

## Exercise

Show the start points (in the WKT format) of all bicycle routes in the table sf_bicycle_routes that have a condition_rating of 2.

### Stuck? Here's a hint!

Use ST_StartPoint inside ST_AsText to get the WKT representation of the start points.