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ALTER TABLE to add a composite primary key
...t it after you recreate the primary key.
Also, when using composite keys, order is important.
These
1) ALTER TABLE provider ADD PRIMARY KEY(person,place,thing);
and
2) ALTER TABLE provider ADD PRIMARY KEY(person,thing,place);
are not the the same thing.
They both enforce uniqueness on that set ...
How to use NSJSONSerialization
I have a JSON string (from PHP's json_encode() that looks like this:
12 Answers
12
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How to apply a function to two columns of Pandas dataframe
...ames in the function instead of indexes then you don't need to worry about order changing, or get the index by name e.g. see stackoverflow.com/questions/13021654/…
– Davos
Mar 22 '18 at 7:19
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Change Bootstrap input focus blue glow
...e="tel"]:focus,
input[type="color"]:focus,
.uneditable-input:focus {
border-color: rgba(126, 239, 104, 0.8);
box-shadow: 0 1px 1px rgba(0, 0, 0, 0.075) inset, 0 0 8px rgba(126, 239, 104, 0.6);
outline: 0 none;
}
sh...
SQL command to display history of queries
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try
cat ~/.mysql_history
this will show you all mysql commands ran on the system
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Is it worth using Python's re.compile?
....compile. If we call it, we bypass the cache. It turns out to be about two orders of magnitude slower for a basic regular expression, such as r'\w+\s+([0-9_]+)\s+\w*'.
Here's my test:
#!/usr/bin/env python
import re
import time
def timed(func):
def wrapper(*args):
t = time.time()
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How to get all subsets of a set? (powerset)
...deally a set) into a list because by a set is a data structure of unique unordered elements, and the order will be crucial to generate the subsets.
selector is key in this algorithm. Note that selector has the same length as the input set, and to make this possible it is using an f-string with padd...
What's the difference between Git Revert, Checkout and Reset?
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Highly active question. Earn 10 reputation in order to answer this question. The reputation requirement helps protect this question from spam and non-answer activity.
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Is there a way to cache GitHub credentials for pushing commits?
...ou need to copy the git-credential-netrc anywhere in your path ($PATH), in order for git to be able to call 'credential-netrc'.
– VonC
Dec 22 '13 at 0:14
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How to make Entity Framework Data Context Readonly
...nly querying capabilities of DbContext. Let's say you have an entity named Order, then you would use ReadOnlyDataContext instance in a way like below.
readOnlyDataContext.Set<Order>().Where(q=> q.Status==OrderStatus.Delivered).ToArray();
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