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DROP IF EXISTS VS DROP?
...table_name;
IF EXISTS is not standard; different platforms might support it with different syntax, or not support it at all. In PostgreSQL, the syntax is
DROP TABLE IF EXISTS table_name;
The first one will throw an error if the table doesn't exist, or if other database objects depend on it. Mo...
How to avoid overflow in expr. A * B - C * D
... long long int A, B, C, D;
Each number can be really big (not overflowing its type). While A*B could cause overflow, at same time expression A*B - C*D can be really small. How can I compute it correctly?
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Is it fine to have foreign key as primary key?
...reign keys are almost always "Allow Duplicates," which would make them unsuitable as Primary Keys.
Instead, find a field that uniquely identifies each record in the table, or add a new field (either an auto-incrementing integer or a GUID) to act as the primary key.
The only exception to this are t...
Automatically deleting related rows in Laravel (Eloquent ORM)
... put the whole thing inside a transaction, to ensure the referential integrity..
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Converting int to bytes in Python 3
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That's the way it was designed - and it makes sense because usually, you would call bytes on an iterable instead of a single integer:
>>> bytes([3])
b'\x03'
The docs state this, as well as the docstring for bytes:
>>>...
How to programmatically send SMS on the iPhone?
Does anybody know if it's possible, and how, to programmatically send a SMS from the iPhone , with the official SDK / Cocoa Touch?
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What's the magic of “-” (a dash) in command-line parameters?
... the tar command, that's common on many commands that want to use a file.
It allows you to specify standard input or output rather than an actual file name.
That's the case for your first and third example. For example, the cdrecord command is taking standard input (the ISO image stream produced b...
Does free(ptr) where ptr is NULL corrupt memory?
... (ptr)
free(ptr);
This is because some C runtimes (I for sure remember it was the case on PalmOS) would crash when freeing a NULL pointer.
But nowadays, I believe it's safe to assume free(NULL) is a nop as per instructed by the standard.
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How to disable postback on an asp Button (System.Web.UI.WebControls.Button)
I have an asp button. It's server-side so I can only show it for logged in users, but i want it to run a javascript function and it seems when it's runat="server" it always calls the postback event.
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How create table only using tag and Css
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edited Apr 21 '17 at 17:31
Martin Nuc
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