doc: use FILTER in aggregate example

Reported-by: [email protected]
Discussion: https://postgr.es/m/163499710897.684.7420075366995883688@wrigleys.postgresql.org

Backpatch-through: 10

diff --git a/doc/src/sgml/query.sgml b/doc/src/sgml/query.sgml
index 71d644f43234513a60baaea87fe6866accd6ba62..9046d7c9fbeaecbe2e0d0d251846f2e63da39958 100644 (file)
--- a/doc/src/sgml/query.sgml
+++ b/doc/src/sgml/query.sgml
@@ -726,19 +726,20 @@ SELECT city, max(temp_lo)
     which gives us one output row per city.  Each aggregate result is
     computed over the table rows matching that city.
     We can filter these grouped
-    rows using HAVING:
+    rows using HAVING and the output count using
+    FILTER:
 
 
-SELECT city, max(temp_lo)
+SELECT city, max(temp_lo), count(*) FILTER (WHERE temp_lo < 30)
     FROM weather
     GROUP BY city
     HAVING max(temp_lo) < 40;
 
 
 
-  city   | max
----------+-----
- Hayward |  37
+  city   | max | count
+---------+-----+-------
+ Hayward |  37 |     5
 (1 row)
 
 
@@ -748,7 +749,7 @@ SELECT city, max(temp_lo)
     names begin with S, we might do:
 
 
-SELECT city, max(temp_lo)
+SELECT city, max(temp_lo), count(*) FILTER (WHERE temp_lo < 30)
     FROM weather
     WHERE city LIKE 'S%'            -- 
     GROUP BY city