Π19016, Π19177, Π19110 - Τελική Εργασία - Συστήματα Διαχείρισης Βάσεων Δεδομένων

mdb.py

@@ -66,8 +66,6 @@ def create_query_plan(query, keywords, action):
             ql.pop(i+1)
             kw_positions.append(i)
         i+=1
-
-
 
     for i in range(len(kw_in_query)-1):
         dic[kw_in_query[i]] = ' '.join(ql[kw_positions[i]+1:kw_positions[i+1]])
@@ -92,11 +90,11 @@ def create_query_plan(query, keywords, action):
 
         else:
             dic['desc'] = None
-
     if action=='create table':
         args = dic['create table'][dic['create table'].index('('):dic['create table'].index(')')+1]
         dic['create table'] = dic['create table'].removesuffix(args).strip()
-        arg_nopk = args.replace('primary key', '')[1:-1]
+        arg_nopk = args.replace('primary key', '')
+        arg_nopk = arg_nopk.replace('unique', '')[1:-1]
         arglist = [val.strip().split(' ') for val in arg_nopk.split(',')]
         dic['column_names'] = ','.join([val[0] for val in arglist])
         dic['column_types'] = ','.join([val[1] for val in arglist])
@@ -105,6 +103,14 @@ def create_query_plan(query, keywords, action):
             dic['primary key'] = arglist[arglist.index('primary')-2]
         else:
             dic['primary key'] = None
+
+        if 'unique' in args:
+            arglist = args[1:-1].replace(',', '')
+            arglist = arglist.split(' ')
+            dic['unique'] = arglist[arglist.index('unique')-2]
+        else:
+            dic['unique'] = None
+
 
     if action=='import': 
         dic = {'import table' if key=='import' else key: val for key, val in dic.items()}
@@ -121,6 +127,36 @@ def create_query_plan(query, keywords, action):
         else:
             dic['force'] = False
 
+    # add action == 'create index'
+    if action == 'create index':
+
+        dic['on'] = dic[kw_in_query[1]]
+        if dic['on'] != "":
+            if '(' in dic[kw_in_query[1]] and ')' in dic[kw_in_query[1]]:
+                condition_split = dic['on'].split()
+                condition_split.remove("(")
+                condition_split.remove(")")
+                dic['on'] = condition_split[0]
+                dic['column'] = condition_split[1]
+            elif '(' in dic[kw_in_query[1]]:
+                raise ValueError('Must be: create index name_of_index on name_table(name_of_column) using btree)')
+            elif ')' in dic[kw_in_query[1]]:
+                raise ValueError('Must be: create index name_of_index on name_table(name_of_column) using btree)')
+        else:
+            raise ValueError('There is no table and column for an index to be created')
+
+        #
+        # if (dic['column'] is not None) and (dic['using'] is not None):
+        #
+        #    dic['using'] = dic[kw_in_query[2]]
+
+
+
+        #dic['create index'] = dic[kw_in_query[0]]
+
+        #    print('Create index')
+
+
     return dic
 
 
@@ -175,9 +211,9 @@ def interpret(query):
                      'unlock table': ['unlock table', 'force'],
                      'delete from': ['delete from', 'where'],
                      'update table': ['update table', 'set', 'where'],
-                     'create index': ['create index', 'on', 'using'],
+                     'create index': ['create index', 'on', 'column', 'using'], #add in query: column
                      'drop index': ['drop index'],
-                     'create view' : ['create view', 'as']
+                     'create view': ['create view', 'as']
                      }
 
     if query[-1]!=';':

miniDB/algebra_rules.py

@@ -0,0 +1,37 @@
+def second_rule(query):
+
+    '''
+    rule 2:
+    σθ1(σθ2(E)) = σθ2(σθ1(E))
+    '''
+
+    newQuery = query
+
+    if 'select' in query.keys() and isinstance(query['from'],dict) and 'select' in query['from'].keys():
+        if not (query['distinct'] == False and query['from']['distinct'] == True and query['where'] !=
+                query['from']['where']):
+
+            if query['limit'] == None and query['from']['limit'] == None:
+
+                newQuery = query
+                newQuery['where'] = newQuery['from']['where']
+                newQuery['from']['where'] = query['where']
+                return [newQuery]
+
+        return []
+
+
+def fifth_rule(query):
+    '''
+    rule 5:
+    E1 ⊲⊳θ E2 = E2 ⊲⊳θ E1
+    '''
+    newQuery = query
+    if 'join' in query.keys():
+        if query['join'] == 'right':
+            newQuery['join'] = 'left'
+        elif query['join'] == 'left':
+            newQuery['join'] = 'right'
+        newQuery['right'] = query['left']
+        newQuery['left'] = query['right']
+    return newQuery