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Add a reference column migration in Rails 4
...t; ActiveRecord::Migration
def change
add_reference :uploads, :user, index: true
end
end
Then, run the migration using rake db:migrate.
This migration will take care of adding a new column named user_id to uploads table (referencing id column in users table), PLUS it will also add an index...
MySQL error: key specification without a key length
...
The error happens because MySQL can index only the first N chars of a BLOB or TEXT column. So The error mainly happens when there is a field/column type of TEXT or BLOB or those belong to TEXT or BLOB types such as TINYBLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, MEDI...
How to remove item from list in C#?
...
List<T> has two methods you can use.
RemoveAt(int index) can be used if you know the index of the item. For example:
resultlist.RemoveAt(1);
Or you can use Remove(T item):
var itemToRemove = resultlist.Single(r => r.Id == 2);
resultList.Remove(itemToRemove);
When yo...
Convert list of dictionaries to a pandas DataFrame
...
How might one use one of the key/value pairs as the index (eg. time)?
– CatsLoveJazz
Jun 28 '16 at 13:37
6
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Convert a Unix timestamp to time in JavaScript
...
Actually it will display time in '10:2:2' format, since it does not add an extra 0 before values below 10.
– Fireblaze
Oct 4 '12 at 14:47
...
How to make lists contain only distinct element in Python? [duplicate]
...ictionary keys, which might be okay for some purposes, but doesn't support indexing for example.
– Mark
Dec 3 '16 at 11:57
...
Use numpy array in shared memory for multiprocessing
...types.c_double, N)
# ...
def f(i): # could be anything numpy accepts as an index such another numpy array
with shared_arr.get_lock(): # synchronize access
arr = np.frombuffer(shared_arr.get_obj()) # no data copying
arr[i] = -arr[i]
Example
import ctypes
import logging
import m...
SQL: capitalize first letter only [duplicate]
... your needs.
)
RETURNS VARCHAR(200)
AS
BEGIN
--Declare Variables
DECLARE @Index INT,
@ResultString VARCHAR(200)--result string size should equal to the @string variable size
--Initialize the variables
SET @Index = 1
SET @ResultString = ''
--Run the Loop until END of the string
WHILE (@Index <LE...
Loop through an array of strings in Bash?
...f an array
arraylength=${#array[@]}
# use for loop to read all values and indexes
for (( i=1; i<${arraylength}+1; i++ ));
do
echo $i " / " ${arraylength} " : " ${array[$i-1]}
done
Output:
1 / 3 : one
2 / 3 : two
3 / 3 : three
...
How to execute shell command in Javascript
...Except for one thing. You'll get the error "child is not a function". The call to exec() executes the command - no need to call child(). Unfortunately, the callback isn't called whenever the child process has something to output - it is called only when the child process exits. Sometimes that's OK a...