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difference between primary key and unique key
...d on multiple columns, e.g. Primary key (CustomerID, ProductID). This is called composite primary key. This is to clarify the first point, as it might be take as it is (read one key => one column ) by new comer to sql : )
– ken
Apr 10 '14 at 13:53
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mysql :: insert into table, data from another table?
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INSERT INTO action_2_members (campaign_id, mobile, vote, vote_date)
SELECT campaign_id, from_number, received_msg, date_received
FROM `received_txts`
WHERE `campaign_id` = '8'
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How to add column if not exists on PostgreSQL?
...statement:
DO $$
BEGIN
BEGIN
ALTER TABLE <table_name> ADD COLUMN <column_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
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Parsing XML with namespace in Python via 'ElementTree'
...tTree is not too smart about namespaces. You need to give the .find(), findall() and iterfind() methods an explicit namespace dictionary. This is not documented very well:
namespaces = {'owl': 'http://www.w3.org/2002/07/owl#'} # add more as needed
root.findall('owl:Class', namespaces)
Prefixes a...
Proper way to wait for one function to finish before continuing?
I have two JS functions. One calls the other. Within the calling function, I'd like to call the other, wait for that function to finish, then continue on. So, for example/pseudo code:
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Declare and Initialize String Array in VBA
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Dim myStringArray() As String
*code*
redim myStringArray(size_of_your_array)
Then you can do something static like this:
myStringArray = { item_1, item_2, ... }
Or something iterative like this:
Dim x
For x = 0 To size_of_your_array
myStringArray(x) = data_source(x).Name
Nex...
In Python, how do I convert all of the items in a list to floats?
I have a script which reads a text file, pulls decimal numbers out of it as strings and places them into a list.
12 Answers...
Why can't I assign a *Struct to an *Interface?
... var pi *Interface
pi = new(Interface)
*pi = ps
_, _ = pi, ps
}
Compiles OK. See also here.
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How can I determine whether a 2D Point is within a Polygon?
...integers. Many systems use integers for UI painting (pixels are ints after all), but macOS for example uses float for everything. macOS only knows points and a point can translate to one pixel, but depending on monitor resolution, it might translate to something else. On retina screens half a point ...
Android getting value from selected radiobutton
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Just a small correction, a very small one rather, you have declared 'rg' twice. It wont make a difference at all, just makes the code more readable.
– SanVed
Aug 19 '18 at 18:06
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