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@UniqueConstraint annotation in Java
...
@Entity
@Table(uniqueConstraints={@UniqueConstraint(columnNames = {"id_1" , "id_2"})})
public class class_name {
@Id
@GeneratedValue
public Long id;
@NotNull
public Long id_1;
@NotNull
public Long id_2;
}
Hope it helped.
...
C# pattern to prevent an event handler hooked twice [duplicate]
...ution and the best one (considering performance) is:
private EventHandler _foo;
public event EventHandler Foo {
add {
_foo -= value;
_foo += value;
}
remove {
_foo -= value;
}
}
No Linq using required. No need to check for null before cancelling a subscrip...
Why do x86-64 systems have only a 48 bit virtual address space?
...
Because that's all that's needed. 48 bits give you an address space of 256 terabyte. That's a lot. You're not going to see a system which needs more than that any time soon.
So CPU manufacturers took a shortcut. They use an instruction set...
Fastest Way to Serve a File Using PHP
...erywhere.
Using the X-SendFile header
As documented by others it's actually the best way. The basis is that you do your access control in php and then instead of sending the file yourself you tell the web server to do it.
The basic php code is :
header("X-Sendfile: $file_name");
header("Conten...
What is the purpose of double curly braces in React's JSX syntax?
... an object literal inlined in the prop value. It's the same as
var obj = {__html: rawMarkup};
<span dangerouslySetInnerHTML={obj} />
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Error 1022 - Can't write; duplicate key in table
...ou can not have the same foreign key names in the database tables.
Check all your tables and all your foreign keys and avoid having two foreign keys with the same exact name.
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Is there a max array length limit in C++?
...se memory is full. For example, a vector<int> of a given size n typically takes multiple times as much memory as an array of type vector<char> (minus a small constant value), since int is usually bigger than char. Therefore, a vector<char> may contain more items than a vector<in...
Java: Date from unix timestamp
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This is the right way:
Date date = new Date ();
date.setTime((long)unix_time*1000);
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Representing Directory & File Structure in Markdown Syntax [closed]
...se ASCII to build the structures, so your example structure becomes
.
+-- _config.yml
+-- _drafts
| +-- begin-with-the-crazy-ideas.textile
| +-- on-simplicity-in-technology.markdown
+-- _includes
| +-- footer.html
| +-- header.html
+-- _layouts
| +-- default.html
| +-- post.html
+-- _po...
How to ignore deprecation warnings in Python
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This doesn't work for me at all, still seeing deprecationwarnings.
– user1244215
Oct 22 '13 at 0:43
9
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