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Best practices for SQL varchar column length [closed]
Every time is set up a new SQL table or add a new varchar column to an existing table, I am wondering one thing: what is the best value for the length .
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Best way to select random rows PostgreSQL
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Given your specifications (plus additional info in the comments),
You have a numeric ID column (integer numbers) with only few (or moderately few) gaps.
Obviously no or few write operations.
Your ID column has to be indexed! A primary key serves nicely.
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How is a tag different from a branch in Git? Which should I use, here?
...particular branch at a moment in time. A branch represents a separate thread of development that may run concurrently with other development efforts on the same code base. Changes to a branch may eventually be merged back into another branch to unify them.
Usually you'll tag a particular version ...
Meaning of Git checkout double dashes
...named master...
git checkout master
Whoops! That changed branches instead. The -- separates the tree you want to check out from the files you want to check out.
git checkout -- master
It also helps us if some freako added a file named -f to our repository:
git checkout -f # wrong
git c...
“Too many values to unpack” Exception
... Stefano BoriniStefano Borini
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What is a “Stub”?
...ouble in movies. (One of his aims was to avoid using any name that was already widely used.) Meszaros then defined four particular kinds of double:
Dummy objects are passed around but never actually used. Usually they are just used to fill parameter lists.
Fake objects actually have workin...
bool operator ++ and --
...e this doesn't work any more (that's still argument enough for it being a bad practice, I'm not defending the practice, just explaining why it works) for a 32-bit int we of course would have to use ++ 2^32 times before this is an issue. With -- though it will only result in false if I started with a...
What is a proper naming convention for MySQL FKs?
... messages(
message_id int,
user_id int
);
ALTER TABLE messages ADD CONSTRAINT fk_messages_users_user_id
FOREIGN KEY (user_id) REFERENCES users(user_id);
I try to stick with the same field names in referencing and referenced tables, as in user_id in the above example. When this is ...
What's the difference between HEAD, working tree and index, in Git?
Can someone tell me the difference between HEAD, working tree and index, in Git?
5 Answers
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What is the difference between NaN and None?
I am reading two columns of a csv file using pandas readcsv() and then assigning the values to a dictionary. The columns contain strings of numbers and letters. Occasionally there are cases where a cell is empty. In my opinion, the value read to that dictionary entry should be None but instead ...