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Does MySQL ignore null values on unique constraints?
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Yes, MySQL allows multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);
INSER...
Ensuring json keys are lowercase in .NET
...m contract resolver for this. The following contract resolver will convert all keys to lowercase:
public class LowercaseContractResolver : DefaultContractResolver
{
protected override string ResolvePropertyName(string propertyName)
{
return propertyName.ToLower();
}
}
Usage:
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Meaning of acronym SSO in the context of std::string
... variables ("from the stack", which are variables that you create without calling malloc / new) are generally much faster than those involving the free store ("the heap", which are variables that are created using new). However, the size of automatic arrays is fixed at compile time, but the size of ...
Should I use multiplication or division?
...wer compared to the lower overhead of the VM. Remember that compilers generally cannot optimize floating point much in order to guarantee precision.
– rasmus
Sep 14 '12 at 7:22
7
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How do you copy the contents of an array to a std::vector in C++ without looping?
... later processing. Since I don't know how many times my function will be called before it is time to process the data, I need a dynamic storage structure, so I chose a std::vector . I don't want to have to do the standard loop to push_back all the values individually, it would be nice if I coul...
How to add a primary key to a MySQL table?
... Column
If you want to add a primary key constraint to an existing column all of the previously listed syntax will fail.
To add a primary key constraint to an existing column use the form:
ALTER TABLE `goods`
MODIFY COLUMN `id` INT(10) UNSIGNED PRIMARY KEY AUTO_INCREMENT;
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Check if multiple strings exist in another string
..., "milk"]
if any(x in a_string for x in matches):
Similarly to check if all the strings from the list are found, use all instead of any.
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Implementing Comments and Likes in database
...ate databases... Currently, I'm creating a website on which a user will be allowed to mark an entity as liked (like in FB), tag it and comment .
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RegEx to parse or validate Base64 data
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The simplest solution would be to strip out all whitespace (which is ignored as per the RFC) before validation.
– Ben Blank
Jan 24 '09 at 1:35
2
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Prefer composition over inheritance?
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Prefer composition over inheritance as it is more malleable / easy to modify later, but do not use a compose-always approach. With composition, it's easy to change behavior on the fly with Dependency Injection / Setters. Inheritance is more rigid as most languages do not allo...