Querying on multiple tables using google apps engine (Python)
If your are looking for join - there is no joins in GAE. BTW, there is pretty easy to make 2 simple queries (Softwares and UserSoftware), and calculate all additional data manually
I have three tables, 1-Users, 2-Softwares, 3-UserSoftwares.
if suppose, Users table having 6 user records(say U1,U2,...,U6) and Softwares table having 4 different softwares(say S1,S2,S3,S4) and UserSoftwares stores the references if a user requested for given software only.
For example: UserSoftwares(5 records) have only two columns(userid, softwareid) which references others. and the data is:
U1   S1
U2   S2
U2   S3
U3   S3
U4   S1
Now I m expecting following results:(if current login user is U2):

S1  Disable
S2  Enable
S3  Enable
S4  Disable
Here, 1st column is softwareid or name and 2nd column is status which having only two values(Enable/Disable) based on UserSoftwares table(model). Note status is not a field of any model(table).
"My Logic is: 
1. loop through each software in softwares model
2. find softwareid with current login userid (U2) in UserSoftwares model: 
    if it found then set status='Enable'
    if not found then set status='Disable'
3. add this status property to software object.
4. repeat this procedure for all softwares. 
"
What should be the query in python google app engine to achieve above result?