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MongoDB: Combine data from multiple collections into one..how?
How can I (in MongoDB) combine data from multiple collections into one collection?
11 Answers
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Can a foreign key be NULL and/or duplicate?
...e that stores sales proposals. Suppose further that each proposal only has one sales person assigned and one client. So your proposal table would have two foreign keys, one with the client ID and one with the sales rep ID. However, at the time the record is created, a sales rep is not always assig...
What are the best practices for SQLite on Android?
...get corrupted.
The basic answer.
The SqliteOpenHelper object holds on to one database connection. It appears to offer you a read and write connection, but it really doesn't. Call the read-only, and you'll get the write database connection regardless.
So, one helper instance, one db connection. ...
Implementing Comments and Likes in database
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The most extensible solution is to have just one "base" table (connected to "likes", tags and comments), and "inherit" all other tables from it. Adding a new kind of entity involves just adding a new "inherited" table - it then automatically plugs into the whole like/ta...
Sibling package imports
...tempted to handle imports in a more rational way but Guido has rejected it one the account of
The only use case seems to be running scripts that happen
to be living inside a module's directory, which I've always seen as an
antipattern.
(here)
Though, I use this pattern on a regular basis ...
Can someone explain mappedBy in JPA and Hibernate?
I am new to hibernate and need to use one-to-many and many-to-one relations. It is a bi-directional relationship in my objects, so that I can traverse from either direction. mappedBy is the recommended way to go about it, however, I couldn't understand it. Can someone explain:
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PostgreSQL: Is it better to use multiple databases with one schema each, or one database with multip
After this comment to one of my question, I'm thinking if it is better using one database with X schemas or vice versa.
5...
Is a one column table good design? [closed]
It it ok to have a table with just one column? I know it isn't technically illegal, but is it considered poor design?
15 A...
get list from pandas dataframe column
...Alternatively you cast it with list(x).
import pandas as pd
data_dict = {'one': pd.Series([1, 2, 3], index=['a', 'b', 'c']),
'two': pd.Series([1, 2, 3, 4], index=['a', 'b', 'c', 'd'])}
df = pd.DataFrame(data_dict)
print(f"DataFrame:\n{df}\n")
print(f"column types:\n{df.dtypes}")
col...
One line if-condition-assignment
...he assignment must actually return something.
As others have already mentioned, you could do this, but it's bad because you'll probably just end up confusing yourself when reading that piece of code the next time:
if someBoolValue: num1=20
I'm not a big fan of the num1 = someBoolValue and 20 or ...