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SQL Server - When to use Clustered vs non-Clustered Index?
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I just want to put in a word of warning: please very carefully pick your clustered index! Every "regular" data table ought to have a clustered index, since having a clustered index does indeed speed up a lot of operations - yes, speed up, even inserts and deletes! But only if y...
Remove file from SVN repository without deleting local copy
How can I "delete" a file which is already in the SVN repository without deleting it from my file system?
5 Answers
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Convert varchar to uniqueidentifier in SQL Server
...E @uuid VARCHAR(50)
SET @uuid = 'a89b1acd95016ae6b9c8aabb07da2010'
SELECT CAST(
SUBSTRING(@uuid, 1, 8) + '-' + SUBSTRING(@uuid, 9, 4) + '-' + SUBSTRING(@uuid, 13, 4) + '-' +
SUBSTRING(@uuid, 17, 4) + '-' + SUBSTRING(@uuid, 21, 12)
AS UNIQUEIDENTIFIER)
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How do you run a single query through mysql from the command line?
... -e "my query"---->ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
– Dr.jacky
Mar 12 '17 at 11:38
2
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Which regular expression operator means 'Don't' match this character?
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You can use negated character classes to exclude certain characters: for example [^abcde] will match anything but a,b,c,d,e characters.
Instead of specifying all the characters literally, you can use shorthands inside character ...
Why does “,,,” == Array(4) in Javascript?
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Because the right hand operand is converted to a string and the string representation of Array(4) is ,,,:
> Array(4).toString()
",,,"
If you use the array constructor function and pass a number, it sets the length of t...
Add hover text without javascript like we hover on a user's reputation
...text. I have seen this at many places and the source code tells me that it can be done without js. And i tried and got only this-
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How to check if an intent can be handled from some activity?
I have this method so far , but it came up like something is missing
6 Answers
6
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How to check if field is null or empty in MySQL?
...LL or field1 = '', 'empty', field1) as field1
from tablename
or
SELECT case when field1 IS NULL or field1 = ''
then 'empty'
else field1
end as field1
from tablename
If you only want to check for null and not for empty strings then you can also use ifnull() or co...
python numpy machine epsilon
...ying to understand what is machine epsilon. According to the Wikipedia, it can be calculated as follows:
3 Answers
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