add examples

README.md

@@ -118,6 +118,12 @@ FROM players
 WHERE <%= partial :email_partial %>
 ```
 
+## Examples
+
+Check examples folder for some usefull queries.
+
+If you have some examples to share please make pull request.
+
 ## Contributing
 
 1. Fork it ( https://github.com/[my-github-username]/sql_query/fork )

examples/README.md

@@ -0,0 +1,10 @@
+### File list:
+
+* __distinct_values.sql.erb__ - implements "loose indexscan" in postgresql. More info [https://wiki.postgresql.org/wiki/Loose_indexscan](https://wiki.postgresql.org/wiki/Loose_indexscan)
+
+```
+SqlQuery.new(:distinct_values, table_name: :players, column_name: :player_type).execute
+
+```
+### 
+

examples/distinct_values.sql.erb

@@ -0,0 +1,14 @@
+WITH RECURSIVE t AS (
+  SELECT MIN(<%= @column_name %>) AS <%= @column_name %>
+  FROM <%= @table_name %>
+  UNION ALL
+  SELECT (
+    SELECT MIN(<%= @column_name %>) FROM <%= @table_name %>
+    WHERE <%= @column_name %> > t.<%= @column_name %>)
+  FROM t WHERE t.<%= @column_name %> IS NOT NULL
+)
+SELECT <%= @column_name %> FROM t WHERE <%= @column_name %> IS NOT NULL
+<% if @with_nulls %>
+  UNION ALL
+  SELECT NULL WHERE EXISTS(SELECT 1 FROM <%= @table_name %> WHERE <%= @column_name %> IS NULL)
+<% end %>