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MySQL Cannot Add Foreign Key Constraint
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mysql> create unique index index_bar_id on foos(bar_id); ... mysql> alter table foos add constraint index_bar_id foreign key (bar_id) references bars (id); sixarm.com/about/…
– CookieCoder
Dec 17 ...
In Python, when to use a Dictionary, List or Set?
... and x not in l
l[i], l[i:j], l[i:j:k]
len(l), min(l), max(l)
l.count(x)
l.index(x[, i[, j]]) - index of the 1st occurrence of x in l (at or after i and before j indeces)
A list also implements all of the mutable sequence operations:
l[i] = x - item i of l is replaced by x
l[i:j] = t - slice of ...
How can I access and process nested objects, arrays or JSON?
...const value = arr[5]; // arr.5 would be a syntax error
// property name / index as variable
const x = 5;
const value = arr[x];
Wait... what about JSON?
JSON is a textual representation of data, just like XML, YAML, CSV, and others. To work with such data, it first has to be converted to JavaScri...
How to delete an element from an array in C#
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If you want to remove all instances of 4 without needing to know the index:
LINQ: (.NET Framework 3.5)
int[] numbers = { 1, 3, 4, 9, 2 };
int numToRemove = 4;
numbers = numbers.Where(val => val != numToRemove).ToArray();
Non-LINQ: (.NET Framework 2.0)
static bool isNotFour(int n)
{
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Postgres NOT in array
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Note that the ANY/ALL operators will not work with array indexes. If indexes are in mind:
SELECT COUNT(*) FROM "messages" WHERE 3 && recipient_ids
and the negative:
SELECT COUNT(*) FROM "messages" WHERE NOT (3 && recipient_ids)
An index can then be created lik...
Heatmap in matplotlib with pcolor?
...pen("http://datasets.flowingdata.com/ppg2008.csv")
nba = pd.read_csv(page, index_col=0)
# Normalize data columns
nba_norm = (nba - nba.mean()) / (nba.max() - nba.min())
# Sort data according to Points, lowest to highest
# This was just a design choice made by Yau
# inplace=False (default) ->tha...
Using varchar(MAX) vs TEXT on SQL Server
...regard to if you should use LIKE to search, or if you should use Full Text Indexing and CONTAINS. This question is the same regardless of VARCHAR(MAX) or TEXT.
If you are searching large amounts of text and performance is key then you should use a Full Text Index.
LIKE is simpler to implement and ...
How to create a file with a given size in Linux?
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See next answer for a better, quicker approach
– elegant dice
Oct 9 '14 at 1:23
2
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“Single-page” JS websites and SEO
...ngine crawler or a user with JavaScript enabled, should all be able to use/index/understand your site's core functionality without issue.
pushState does not add to this burden, in my experience. It only brings what used to be an afterthought and "if we have time" to the forefront of web developmen...
Asynchronous Process inside a javascript for loop [duplicate]
...e some time in the future and call their callbacks, the value of your loop index variable i will be at its last value for all the callbacks.
This is because the for loop does not wait for an asynchronous operation to complete before continuing on to the next iteration of the loop and because the ...