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How do I update if exists, insert if not (AKA “upsert” or “merge”) in MySQL?
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edited Jul 15 at 20:25
answered Aug 2 '09 at 13:35
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Regular expression for a hexadecimal number?
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How about the following?
0[xX][0-9a-fA-F]+
Matches expression starting with a 0, following by either a lower or uppercase x, followed by one or more characters in the ranges 0-9, or a-f, or A-F
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List of installed gems?
... Gem::Requirement.default)
specs = Gem.source_index.search(dep)
puts specs[0..5].map{ |s| "#{s.name} #{s.version}" }
# >> Platform 0.4.0
# >> abstract 1.0.0
# >> actionmailer 3.0.5
# >> actionpack 3.0.5
# >> activemodel 3.0.5
# >> activerecord 3.0.5
Here's an ...
How to get 0-padded binary representation of an integer in java?
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201
I think this is a suboptimal solution, but you could do
String.format("%16s", Integer.toBinary...
Can PostgreSQL index array columns?
... CREATE TABLE "Test"("Column1" int[]);
INSERT INTO "Test" VALUES ('{10, 15, 20}');
INSERT INTO "Test" VALUES ('{10, 20, 30}');
CREATE INDEX idx_test on "Test" USING GIN ("Column1");
-- To enforce index usage because we have only 2 records for this test...
SET enable_seqscan ...
0.1 float is greater than 0.1 double. I expected it to be false [duplicate]
...loat. float has 24 binary bits of precision, and double has 53. In binary, 0.1 is:
0.1₁₀ = 0.0001100110011001100110011001100110011001100110011…₂
^ ^ ^ ^
1 10 20 24
So if we round up at the 24th digit, we'll get
0.1₁₀ ~ 0.00011...
What is the difference between String.slice and String.substring?
...nts.
If either argument is negative or is NaN, it is treated as if it were 0.
Distinctions of slice():
If start > stop, slice() will return the empty string. ("")
If start is negative: sets char from the end of string, exactly like substr() in Firefox. This behavior is observed in both Firefo...
C# equivalent to Java's charAt()?
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201
You can index into a string in C# like an array, and you get the character at that index.
Exam...
What do 'real', 'user' and 'sys' mean in the output of time(1)?
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2130
Real, User and Sys process time statistics
One of these things is not like the other. Real ref...
Read a zipped file as a pandas DataFrame
...long form:
df = pd.read_csv('filename.zip', compression='zip', header=0, sep=',', quotechar='"')
Description of the compression argument from the docs:
compression : {‘infer’, ‘gzip’, ‘bz2’, ‘zip’, ‘xz’, None}, default ‘infer’
For on-the-fly decompression of on-d...