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When and why are database joins expensive?
...s back to mitigating the size of the working set. Joins involving properly selected keys with correctly set up indexes are cheap, not expensive, because they allow significant pruning of the result before the rows are materialised.
Materialising the result involves bulk disk reads which are the mo...
How do I ignore ampersands in a SQL script running from SQL Plus?
..., I've chose the # character, but that choice is just an example.
SQL> select '&var_ampersand #var_hash' from dual;
Enter value for var_ampersand: a value
'AVALUE#VAR_HASH'
-----------------
a value #var_hash
SQL> set define #
SQL> r
1* select '&var_ampersand #var_hash' from du...
Algorithm to implement a word cloud like Wordle
...ou color and size words based on different weightings and it supports word selection (from a coordinate) and selected word highlighting. The source is yours to use as you see fit.
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Warning - Build path specifies execution environment J2SE-1.4
... "JRE System Library[J2SE 1.4]"
Click Add Library -> JRE System Library
Select the new "Execution Environment" or Workspace default JRE
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Is there a best practice for generating html with javascript
...$.template('<div><img src="${url}" />${name}</div>');
$(selector).append( t , {
url: jsonObj.url,
name: jsonObj.name
});
I say go the cool route (and better performing, more maintainable), and use templating.
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gdb fails with “Unable to find Mach task port for process-id” error
...Self Signed Root”, set “Certificate Type” to “Code Signing” and select the “Let me override defaults”. Click “Continue”.
You might want to extend the predefined 365 days period to 3650 days.
Click several times on “Continue” until you get to the “Specify a Location For The Ce...
“Width equals height” constraint in Interface Builder
...click and drag from a view and release while the pointer is over the view. Select "Aspect Ratio". It will create a constraint where the first and second item is the view.
Before Xcode 5.1
You can't because the width/height editor lacks the fields to relate to another property or set the ratio:
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Serialize form data to JSON [duplicate]
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@DaniëlCamps is right. A <select multiple> with more than one option selected will fail.
– Vanderlei Pires
Oct 4 '18 at 17:25
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How to set environment variables in Jenkins?
...
Go to your job Configure screen
Find Add build step in Build section and select Inject environment variables
Set the desired environment variable as VARIABLE_NAME=VALUE pattern. In my case, I changed value of USERPROFILE variable
If you need to define a new environment variable depending on so...
How do I return rows with a specific value first?
...to treat boolean expressions as having a numeric value, then you can use:
SELECT *
FROM `Users`
ORDER BY (`city` = 'New York') DESC, `city`
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