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How to count occurrences of a column value efficiently in SQL?
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If you're using Oracle, then a feature called analytics will do the trick. It looks like this:
select id, age, count(*) over (partition by age) from students;
If you aren't using Oracle, then you'll need to join back to the counts:
select a.id, a.age, b.age_co...
Properly escape a double quote in CSV
...le double quote to escape a double quote. You can use a command-line tool called csvfix to detect any lines which don't conform: csvfix check -nl -v [filename]
– Sam Critchley
Jun 30 '16 at 14:51
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Which is faster: multiple single INSERTs or one multiple-row INSERT?
... How many rows i can insert at a time using single insert statement. is it allow me to insert 10000 rows at a time?
– Naresh Ramoliya
Apr 30 '16 at 8:02
10
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How to reset a timer in C#?
...ype: System.Int32 The
amount of time to delay before the
invoking the callback method specified
when the Timer was constructed, in
milliseconds. Specify
Timeout.Infinite to prevent the
timer from restarting. Specify zero
(0) to restart the timer immediately.
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For each row in an R dataframe
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How do you actually implement (row)? Is it dataframe$column? dataframe[somevariableNamehere]? How do you actually say its a row. The pseudocode "function(row) dostuff" how would that actually look?
– uh_big_mike_boi...
What is the difference between .map, .every, and .forEach?
I've always wondered what the difference between them were. They all seem to do the same thing...
4 Answers
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How to generate a Dockerfile from an image?
...;image_id>
-f, --full-tree Generate Dockerfile for all parent layers
-h, --help Show this message
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Test if a class has an attribute?
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to only check if the attribute is present, which is usually all that is needed for parameterless/propertyless attributes, it's cheaper to use .IsDefined, as it will query the metadata, and not deserialize and instantiate the attribute object.
– Lasse V. Karl...
facebook: permanent Page Access Token?
...ook pages as one of its data sources. It imports some data from it periodically with no GUI involved. Then we use a web app to show the data we already have.
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Select objects based on value of variable in object using jq
...t work: termux-contact-list |jq -r '.[] | select(.name=="$1")|.number'. I call it like cool_fn Name1. However, this works: termux-contact-list |jq -r '.[] | select(.name=="Name1")|.number'
– Timo
Aug 18 '18 at 8:13
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