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How to use GROUP BY to concatenate strings in MySQL?
...n_group-concat
From the link above, GROUP_CONCAT: This function returns a string result with the concatenated non-NULL values from a group. It returns NULL if there are no non-NULL values.
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Breaking up long strings on multiple lines in Ruby without stripping newlines
... be wider than 80 characters. Since this is a Rails project, we often have strings that are a little bit longer - i.e. " User X wanted to send you a message about Thing Y " that doesn't always fit within the 80 character style limit.
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Different ways of adding to Dictionary
...e value of the key if it already exists in the dictionary.
IDictionary<string, string> strings = new Dictionary<string, string>();
strings["foo"] = "bar"; //strings["foo"] == "bar"
strings["foo"] = string.Empty; //strings["foo"] == string.empty
strings.Add("foo", "bar"); ...
Why is enum class preferred over plain enum?
...this is usually an int. Also each enumerated type shall be compatible with char or a signed/unsigned integer type.
This is a wide description of what an enum underlying type must be, so each compiler will take decisions on his own about the underlying type of the classic enum and sometimes the resu...
How do C++ class members get initialized if I don't do it explicitly?
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For objects, their default constructor is called. For example, for std::string, the default constructor sets it to an empty string. If the object's class does not have a default constructor, it will be a compile error if you do not explicitly initialize it.
For primitive types (pointers, ints, e...
Should Gemfile.lock be included in .gitignore?
...> Always check in Gemfile.lock, make travis delete it if you want to be extra thorough https://grosser.it/2015/08/14/check-in-your-gemfile-lock/
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How does delete[] know it's an array?
...oo;
then the memory space that's allocated for foo shouldn't include any extra overhead that would be needed to support arrays of Foo.
Since only array allocations are set up to carry the extra array size information, you then need to tell the runtime libraries to look for that information when y...
How do I compare strings in Java?
I've been using the == operator in my program to compare all my strings so far.
However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.
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Understanding the difference between Object.create() and new SomeFunction()
....create(Car.prototype) — When you create an object like this you have an extra option to choose your object's {prototype} property. If you want Car.prototype as the {prototype} then pass it as a parameter in the function. If you don't want any {prototype} for your object then you can pass null lik...
JSON.NET Error Self referencing loop detected for type
...class Category
{
public int Id { get; set; }
public string Name { get; set; }
[JsonIgnore]
[IgnoreDataMember]
public virtual ICollection<Product> Products { get; set; }
}
JsonIgnore is for JSON.NET and IgnoreDataMember is for Xml...