Mining computations update

* Added a few that can be used to retrieve mining settings for resource
providers from empire-owned planets from either the empire-wide or
planet-specific settings

legacyworlds-server-data/db-structure/parts/040-functions/145-resource-providers.sql

@@ -59,3 +59,43 @@ REVOKE EXECUTE
 		DOUBLE PRECISION , DOUBLE PRECISION ,
 		DOUBLE PRECISION )
 	FROM PUBLIC;
+
+
+
+/*
+ * Mining settings view
+ * ---------------------
+ *
+ * This view lists mining settings being used on planets owned by empires
+ * for each resource providers. The settings are taken from planet-specific
+ * settings if they are available, or from empire-wide settings.
+ * 
+ * Columns:
+ *
+ *		planet_id			The planet's identifier
+ *		resource_name_id	The type of resources
+ *		mset_weight			The setting to use for mining priorities
+ *		mset_specific		True if the settings are specific for this planet,
+ *								false if empire-wise settings are in use. 
+ */
+DROP VIEW IF EXISTS emp.mining_settings_view CASCADE;
+CREATE VIEW emp.mining_settings_view
+	AS SELECT planet_id , resource_name_id ,
+				( CASE
+					WHEN _pl_settings.planet_id IS NULL THEN
+						_emp_settings.empmset_weight
+					ELSE
+						_pl_settings.emppmset_weight
+				END ) AS mset_weight ,
+				( _pl_settings.planet_id IS NOT NULL ) AS mset_specific
+			FROM verse.resource_providers
+				INNER JOIN emp.planets
+					USING ( planet_id )
+				INNER JOIN emp.mining_settings _emp_settings
+					USING ( empire_id , resource_name_id )
+				LEFT OUTER JOIN emp.planet_mining_settings _pl_settings
+					USING ( planet_id , empire_id , resource_name_id );
+
+GRANT SELECT
+	ON emp.mining_settings_view
+	TO :dbuser;