Merge pull request orbisgis#964 from gpetit/gh-pages

update GeoJsonWrite doc

docs/dev/GeoJsonWrite.md

@@ -13,21 +13,47 @@ permalink: /docs/dev/GeoJsonWrite/
 
 {% highlight mysql %}
 GeoJsonWrite(VARCHAR path, VARCHAR tableName);
+GeoJsonWrite(VARCHAR path, VARCHAR tableName, VARCHAR fileEncoding);
 {% endhighlight %}
 
 ### Description
 
-Writes table `tableName` to a [GeoJSON][wiki] file located at
+Writes the contents of table `tableName` to a [GeoJSON][wiki] file located at
 `path`.
 
+`tableName` can be either:
+
+* the name of an existing table,
+* the result of a query (`SELECT` instruction which has to be written between simple quote and parenthesis `'( )'`).
+
+The default value of `fileEncoding` is `ISO-8859-1`.
+
 ### Examples
 
 {% highlight mysql %}
 -- Write a spatial table to a GeoJSON file:
 CREATE TABLE TEST(ID INT PRIMARY KEY, THE_GEOM POINT);
 INSERT INTO TEST VALUES (1, 'POINT(0 1)');
+INSERT INTO TEST VALUES (2, 'POINT(2 4)');
+
 CALL GeoJsonWrite('/home/user/test.geojson', 'TEST');
 
+-- Read it back:
+CALL GeoJsonRead('/home/user/test.geojson', 'TEST2');
+SELECT * FROM TEST2;
+-- Answer:
+-- | THE_GEOM    | ID |
+-- |-------------|----|
+-- | POINT(0 1)  | 1  |
+-- | POINT(2 4)  | 2  |
+{% endhighlight %}
+
+#### Case where `tablename` is the result of a selection
+
+{% highlight mysql %}
+CALL GeoJsonWrite('/home/user/test.geojson', 
+                  '(SELECT * FROM TEST WHERE ID<2 )');
+
 -- Read it back:
 CALL GeoJsonRead('/home/user/test.geojson', 'TEST2');
 SELECT * FROM TEST2;