Add support for executing arbitrary queries and commands

Mostly intended for use with schema exploration and management commands

Author: Enric Sala

README.md

@@ -170,6 +170,27 @@ ttable = weather.timetable('Europe/Paris');
 
 Notice that the `time()` and `timetable()` methods take an optional timezone argument.
 
+Other commands
+--------------
+
+Use `runCommand(command, requiresPost)` for executing commands not provided in the library:
+
+```matlab
+% Show series and tag keys in a database
+influxdb.runCommand('SHOW SERIES ON "example" FROM "weather"');
+influxdb.runCommand('SHOW TAG KEYS ON "example" FROM "weather"');
+
+% Create and drop a database
+influxdb.runCommand('CREATE DATABASE "example"', true);
+influxdb.runCommand('DROP DATABASE "example"', true);
+
+% Create a retention policy that keeps data for one day
+influxdb.runCommand('CREATE RETENTION POLICY "one_day" ON "example" DURATION 1d REPLICATION 1', true);
+influxdb.runCommand('SHOW RETENTION POLICIES ON "example"', false);
+```
+
+See the [InfluxDB documentation][influxdb-docs] for more schema exploration and management commands.
+
 
 Contributing
 ------------

influxdb-client/InfluxDB.m

@@ -106,6 +106,19 @@
         function builder = writer(obj)
             builder = WriteBuilder().influxdb(obj);
         end
+        
+        % Execute other queries or commands
+        function response = runCommand(obj, command, requiresPost)
+            url = [obj.Url '/query'];
+            opts = weboptions('Username', obj.User, 'Password', obj.Password);
+            if nargin > 2 && requiresPost
+                opts.Timeout = obj.WriteTimeout;
+                response = webwrite(url, 'q', command, opts);
+            else
+                opts.Timeout = obj.ReadTimeout;
+                response = webread(url, 'q', command, opts);
+            end
+        end
     end
 
 end