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MySQL foreign key constraints, cascade delete
...#2 (blue):
DELETE FROM categories WHERE (id = 2);
the DBMS will look at all the tables which have a foreign key pointing at the 'categories' table, and delete the records where the matching id is 2. Since we only defined the foreign key relationship in products_categories, you end up with this ta...
Convert Existing Eclipse Project to Maven Project
...atic importer or wizard?': not that I know of. Using the option above will allow you to enable the m2eclipse plugin for your existing project avoiding the manual copying. You will still need to actually set up the dependencies and other stuff you need to build yourself.
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How to check if DST (Daylight Saving Time) is in effect, and if so, the offset?
...et returns positive numbers of minutes for zones west of UTC, which are usually stated as negative hours (since they're "behind" UTC). For example, Los Angeles is UTC–8h Standard, UTC-7h DST. getTimezoneOffset returns 480 (positive 480 minutes) in December (winter, Standard Time), rather than -480...
Why does my application spend 24% of its life doing a null check?
...t store a copy of the bytes in RAM. An important one is the L1 cache, typically 16 kilobytes for data and 16 kilobytes for instructions. Small, allowing it to be close to the execution engine. Reading bytes from the L1 cache typically takes 2 or 3 CPU cycles. Next up is the L2 cache, bigger and slow...
How do I install ASP.NET MVC 5 in Visual Studio 2012?
Is there a way to install ASP.NET MVC 5 in Visual Studio 2012?
11 Answers
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Why are ToLookup and GroupBy different?
... I ever bother with GroupBy? Why should it exist?
What happens when you call ToLookup on an object representing a remote database table with a billion rows in it?
The billion rows are sent over the wire, and you build the lookup table locally.
What happens when you call GroupBy on such an object...
Test or check if sheet exists
Basically I loop through all sheets in the origin workbook then set destsheet in the destination workbook to the sheet with the same name as the currently iterated one in the origin workbook.
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'size_t' vs 'container::size_type'
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The standard containers define size_type as a typedef to Allocator::size_type (Allocator is a template parameter), which for std::allocator<T>::size_type is typically defined to be size_t (or a compatible type). So for the standard case, they are the same.
However, if you us...
How to exclude specific folders or files from validation in Eclipse?
...lder
Click Resource, ResourceFilters
Click "Add"
Set the following Exclude All, Files and Folders, All Children, add an asterisk (*) to the File and Folder Attributes input field (highlighted in the image below)
Note: In Eclipse Indigo you have to Right click the folder and select properties and t...
How to find all tables that have foreign keys that reference particular table.column and have values
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This solution will not only display all relations but also the constraint name, which is required in some cases (e.g. drop constraint):
SELECT
CONCAT(table_name, '.', column_name) AS 'foreign key',
CONCAT(referenced_table_name, '.', referenced_column_n...