README.md in pgrel-0.1.3 vs README.md in pgrel-0.2.0

@@ -4,33 +4,39 @@
 
 ActiveRecord extension for querying hstore, array and jsonb.
 
 Compatible with **Rails** >= 4.2.
 
-### General
-
-The functionality is based on ActiveRecord `WhereChain`. 
-To start querying call `where(:store_name)` and chain it with store-specific call (see below).
-
 #### Install
 
 In your Gemfile:
 
 ```ruby
-gem "pgrel", "~>0.1"
+gem "pgrel", "~> 0.2"
 ```
 
 ### HStore
 
+#### Querying
+
+The functionality is based on ActiveRecord `WhereChain`. 
+To start querying call `where(:store_name)` and chain it with store-specific call (see below).
+
 Query by key value:
 
 ```ruby
 Hstore.where.store(:tags, a: 1, b: 2)
 #=> select * from hstores where tags @> '"a"=>"1","b"=>"2"'
 
 Hstore.where.store(:tags, a: [1, 2])
 #=> select * from hstores where (tags @> '"a"=>"1"' or tags @> '"a"=>"2"')
+
+Hstore.where.store(:tags, :a)
+#=> select * from hstores where (tags @> '"a"=>NULL')
+
+Hstore.where.store(:tags, { a: 1 }, { b: 2 })
+#=> select * from hstores where (tags @> '"a"=>"1" or tags @> "b"=>"2"')
 ```
 
 Keys existence:
 
 ```ruby
@@ -45,22 +51,58 @@
 # Retrieve items that have either key 'a' or 'b' in 'tags'::hstore
 Hstore.where.store(:tags).any('a', 'b')
 #=> select * from hstores where tags ?| array['a', 'b']
 ```
 
+Values existence:
+
+```ruby
+# Retrieve items that have value '1' OR '2'
+Hstore.where.store(:tags).value(1, 2)
+#=> select * from hstores where (avals(tags) @> ARRAY['1'] OR avals(tags) @> ARRAY['2'] )
+
+# Retrieve items that have values '1' AND '2'
+Hstore.where.store(:tags).values(1, 2)
+#=> select * from hstores where (avals(tags) @> ARRAY['1', '2'])
+```
+
 Containment:
 
 ```ruby
 Hstore.where.store(:tags).contains(a: 1, b: 2)
 #=> select * from hstores where tags @> '\"a\"=>\"1\", \"b\"=>\"2\"'
 
 Hstore.where.store(:tags).contained(a: 1, b: 2)
 #=> select * from hstores where tags <@ '\"a\"=>\"1\", \"b\"=>\"2\"'
 ```
 
+#### Update
+
+Is implemented through `ActiveRecord::Store::FlexibleHstore` and `ActiveRecord::Store::FlexibleJsonb`
+objects. You can get them by sending `update_store(store_name)` to relation or class.
+
+Add key, value pairs:
+
+```ruby
+Hstore.update_store(:tags).merge(new_key: 1, one_more: 2)
+Hstore.update_store(:tags).merge([[:new_key, 1], [:one_more, 2]])
+```
+
+Delete keys:
+
+```ruby
+Hstore.update_store(:tags).delete_keys(:a, :b)
+```
+
+Delete key, value pairs:
+
+```ruby
+Hstore.update_store(:tags).delete_pairs(a: 1, b: 2)
+```
+
 ### JSONB
 
-All queries for Hstore also available for JSONB.
+All queries and updates for Hstore also available for JSONB.
 
 **NOTE**. Querying by array value always resolves to `(... or ...)` statement. 
 Thus it's impossible to query json array value, e.g.:
 
 ```ruby