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update and delete now return the number of affected rows

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git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@77 014f5005-505e-4b48-8d0a-63407b615a7c
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LtWorf 2008-12-25 11:37:11 +00:00
parent fd5e8dd276
commit 600e6ee1e0
1 changed files with 10 additions and 3 deletions
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13
relation.py
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@ -424,7 +424,9 @@ class relation (object):
This operation will change the relation itself instead of generating a new one, This operation will change the relation itself instead of generating a new one,
updating all the touples that make expr true. updating all the touples that make expr true.
Dic must be a dictionary that has the form field name:value. Every kind of value Dic must be a dictionary that has the form field name:value. Every kind of value
will be converted into a string''' will be converted into a string.
Returns the number of affected rows.'''
affected=0
attributes={} attributes={}
keys=dic.keys() #List of headers to modify keys=dic.keys() #List of headers to modify
f_ids=self.header.getAttributesId(keys) #List of indexes corresponding to keys f_ids=self.header.getAttributesId(keys) #List of indexes corresponding to keys
@ -442,15 +444,18 @@ class relation (object):
else: else:
attributes[self.header.attributes[j]]=i[j] attributes[self.header.attributes[j]]=i[j]
if eval(expr,attributes): #If expr is true, changing the touple if eval(expr,attributes): #If expr is true, changing the touple
affected+=1
for k in range(len(keys)): for k in range(len(keys)):
i[f_ids[k]]=str(dic[keys[k]]) i[f_ids[k]]=str(dic[keys[k]])
return affected
def delete(self,expr): def delete(self,expr):
'''Delete, expr must be a valid boolean expression, can contain field names, '''Delete, expr must be a valid boolean expression, can contain field names,
constant, math operations and boolean ones. constant, math operations and boolean ones.
This operation will change the relation itself instead of generating a new one, This operation will change the relation itself instead of generating a new one,
deleting all the touples that make expr true.''' deleting all the touples that make expr true.
Returns the number of affected rows.'''
attributes={} attributes={}
affected=len(self.content)
new_content=[] #New content of the relation new_content=[] #New content of the relation
for i in self.content: for i in self.content:
for j in range(len(self.header.attributes)): for j in range(len(self.header.attributes)):
@ -463,8 +468,10 @@ class relation (object):
else: else:
attributes[self.header.attributes[j]]=i[j] attributes[self.header.attributes[j]]=i[j]
if not eval(expr,attributes): if not eval(expr,attributes):
affected-=1
new_content.append(i) new_content.append(i)
self.content=new_content self.content=new_content
return affected
class header (object): class header (object):
'''This class defines the header of a relation. '''This class defines the header of a relation.