DOC: more documentation

procedures/query/applyPOV.sql

@@ -21,14 +21,20 @@
  * ** end header
  */
 
+/* Documentation including (?) has to be checked by an expert. */
+
 DROP PROCEDURE IF EXISTS db_2_0.applyPOV;
 DELIMITER //
 
-CREATE PROCEDURE db_2_0.applyPOV(in sourceSet VARCHAR(255),
-                                 in targetSet VARCHAR(255),
+CREATE PROCEDURE db_2_0.applyPOV(in sourceSet VARCHAR(255), /* (?) Name of the table that the POV will be applied to. This can be a temporary table. */
+                                 in targetSet VARCHAR(255), /* (?) Name of the result table of this POV. */
                                  in propertiesTable VARCHAR(255),
                                  in refIdsTable VARCHAR(255),
-                                 in o CHAR(4),
+                                 in o CHAR(4), /* The operator for this operation. can be one of:
+                                                    0   check for "equals NULL"
+                                                    !0  check for "not NULL"
+                                                    ->  check whether a reference exists
+                                               */
                                  in vText VARCHAR(255),
                                  in vInt INT,
                                  in vDouble DOUBLE,
@@ -65,6 +71,8 @@ POV_LABEL: BEGIN
         SET vText = NULL;
         SET sTextData = 'SELECT domain_id, entity_id, property_id FROM `null_data` AS subdata';
 
+        /* Question: in !0 the query is explicitly checked for NOT NULL. Aren't these NULL entries forgotten here? */
+
     ELSEIF o = '!0' THEN
         #-- special case: property IS NOT NULL
         #-- generate statement parts