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Why is LINQ JOIN so much faster than linking with WHERE?
...nce they work directly in memory (Linq to DataSet)
The query with multiple tables and a Where condition actually performs a cartesian product of all the tables, then filters the rows that satisfy the condition. This means the Where condition is evaluated for each combination of rows (n1 * n2 * n3 * ...
UITableview: How to Disable Selection for Some Rows but Not Others
I am displaying in a group tableview contents parsed from XML. I want to disable the click event on it (I should not be able to click it at all) The table contains two groups. I want to disable selection for the first group only but not the second group. Clicking the first row of second group nav...
Remove duplicated rows
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The data.table package also has unique and duplicated methods of it's own with some additional features.
Both the unique.data.table and the duplicated.data.table methods have an additional by argument which allows you to pass a chara...
Creating and Update Laravel Eloquent
...built in L4 functionality for doing this in some way such as:
$row = DB::table('table')->where('id', '=', $id)->first();
// Fancy field => data assignments here
$row->save();
I did create this method a few weeks back...
// Within a Model extends Eloquent
public static function creat...
Is there a MySQL command to convert a string to lowercase?
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UPDATE table SET colname=LOWER(colname);
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Warning: Null value is eliminated by an aggregate or other SET operation in Aqua Data Studio
... solve this problem?. How to change the null data to 0 when no data in the table?.
6 Answers
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Sorting arrays in NumPy by column
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You can sort on multiple columns as per Steve Tjoa's method by using a stable sort like mergesort and sorting the indices from the least significant to the most significant columns:
a = a[a[:,2].argsort()] # First sort doesn't need to be stable.
a = a[a[:,1].argsort(kind='mergesort')]
a = a[a[:,...
What are file descriptors, explained in simple terms?
...file in operating system.
If your process opens 10 files then your Process table will have 10 entries for file descriptors.
Similarly when you open a network socket, it is also represented by an integer and it is called Socket Descriptor.
I hope you understand.
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What's the Hi/Lo algorithm?
...re out the next identifier value knowing we use hilo in this particular DB table?
– Vlad Mihalcea
Feb 7 '17 at 1:46
My...
Get Specific Columns Using “With()” Function in Laravel Eloquent
I have two tables, User and Post . One User can have many posts and one post belongs to only one user .
13 Answe...