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How do I check to see if a value is an integer in MySQL?
...e REGEXP operator, matching the string to a regular expression. Simply do
select field from table where field REGEXP '^-?[0-9]+$';
this is reasonably fast. If your field is numeric, just test for
ceil(field) = field
instead.
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Best way to test if a generic type is a string? (C#)
..., UInt16, Int32, UInt32, Int64, UInt64, Single, Double, Decimal, DateTime, Char, and String, so you can check for primitive types using this. More info on "Generic Type Checking".
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Select rows of a matrix that meet a condition
...20, ncol = 4)
colnames(m) <- letters[1:4]
The following command will select the first row of the matrix above.
subset(m, m[,4] == 16)
And this will select the last three.
subset(m, m[,4] > 17)
The result will be a matrix in both cases.
If you want to use column names to select columns...
Android List Preferences: have summary as selected value?
...ile. How would I set the summary of the list activity to the value that is selected?
11 Answers
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Does Ruby have a string.startswith(“abc”) built in method?
...n building regexes out of string literals - remember to escape any special chars. there is a function for that fi the strings literals can be unpredictable
– Radu Simionescu
Nov 1 '17 at 8:40
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Access-Control-Allow-Origin wildcard subdomains, ports and protocols
...use that's the correct way to do it (even though . is the only regexp meta char valid in a DNS name, preg_quote() describes the intended operation better)
– DaveRandom
Jul 20 '15 at 0:13
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Define static method in source-file with declaration in header-file in C++
...case,
static void CP_StringToPString( std::string& inString, unsigned char *outString);
Since your member function CP_StringToPstring is static, the parameters in that function, inString and outString should be declared as static too.
The static member functions does not refer to the object ...
Select first 4 rows of a data.frame in R
How can I select the first 4 rows of a data.frame :
5 Answers
5
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Change name of iPhone app in Xcode 4
...veryone:
1.In the project contents pane at left, click the Folder icon.
2.Select the top-level blue line representing the project.
3.If you don't have the Inspector pane (right pane) open, click the button to enable it. This is the third button in the "View" toolbar towards the upper right corner...
How do I check if an index exists on a table field in MySQL?
...
Try:
SELECT * FROM information_schema.statistics
WHERE table_schema = [DATABASE NAME]
AND table_name = [TABLE NAME] AND column_name = [COLUMN NAME]
It will tell you if there is an index of any kind on a certain column wi...