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Transaction isolation levels relation with locks on table
...st insecure way to work with data since can lead to data holes in not physically related tables (yes, two tables can be logically but not physically related in real-world apps =\).
READ COMMITTED - lock on committed data. You can read the data that was only committed. This means A writes data and B ...
Foreign key constraint may cause cycles or multiple cascade paths?
...lter your design (or doing so would compromise things) then you should consider using triggers as a last resort.
FWIW resolving cascade paths is a complex problem. Other SQL products will simply ignore the problem and allow you to create cycles, in which case it will be a race to see which will ove...
sqlalchemy unique across multiple columns
... that represents locations. Locations "belong" to customers. Locations are identified by a unicode 10 character code. The "location code" should be unique among the locations for a specific customer.
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How to open a second activity on click of button in android app
I am learning to build android applications and I need some specific help. I can't seem to get my head around which bits of template code I am required to change, and which bits are static.
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MongoDB and “joins” [duplicate]
...s to do it manually, as you have almost described. Just save a document's _id in another document's other_id, then write your own function to resolve the relationship. The other solution is to use DBRefs as described on the manual page above, which will make MongoDB resolve the relationship client-s...
Python - write() versus writelines() and concatenated strings
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More specifically, writelines expects an iterable. You can use a list, a tuple, or a generator.
– Mark Ransom
Sep 11 '12 at 20:52
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twitter bootstrap navbar fixed top overlapping site
...ifts up like the navbar isn't there and the navbar overlaps it. here's basically how i laid it out:
18 Answers
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SQL update from one Table to another based on a ID match
... Sales_Import SI
INNER JOIN
RetrieveAccountNumber RAN
ON
SI.LeadID = RAN.LeadID;
MySQL and MariaDB
UPDATE
Sales_Import SI,
RetrieveAccountNumber RAN
SET
SI.AccountNumber = RAN.AccountNumber
WHERE
SI.LeadID = RAN.LeadID;
...
LEFT OUTER JOIN in LINQ
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If a database driven LINQ provider is used, a significantly more readable left outer join can be written as such:
from maintable in Repo.T_Whatever
from xxx in Repo.T_ANY_TABLE.Where(join condition).DefaultIfEmpty()
If you omit the DefaultIfEmpty() yo...
How can I run an external command asynchronously from Python?
... has the advantage of servicing the early-finishing requests first. If you call communicate on the first running process and that turns out to run the longest, the other running processes will have been sitting there idle when you could have been handling their results.
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