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What are database normal forms and can you give examples? [closed]
.... Recall that a primary key can be made up of multiple columns. As Chris said in his response:
The data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF] (so help me Codd).
2NF
Say you have a table containing courses that are taken in a certain semester, and you have the...
android fragment- How to save states of views in a fragment when another fragment is pushed on top o
In android, a fragment (say FragA ) gets added to the backstack and another fragment (say FragB ) comes to the top. Now on hitting back FragA comes to the top and the onCreateView() is called. Now I had FragA in a particular state before FragB got pushed on top of it.
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The object cannot be deleted because it was not found in the ObjectStateManager
... instance). Try this:
protected MyEntities sqlEntities;
public virtual void Delete(TEntity entity)
{
sqlEntities.Attach(entity);
sqlEntities.DeleteObject(entity);
sqlEntities.SaveChanges();
}
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XPath query to get nth instance of an element
...do not control) that has several input elements all with the same fixed id attribute of "search_query" . The contents of the file can change, but I know that I always want to get the second input element with the id attribute "search_query" .
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belongs_to through associations
...tion cannot have a :through option. You're better off caching the question_id on Choice and adding a unique index to the table (especially because validates_uniqueness_of is prone to race conditions).
If you're paranoid, add a custom validation to Choice that confirms that the answer's question_id ...
WebView and HTML5
... our websites... Pretty simple with the WebViewClient . until I hit the video.
13 Answers
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Difference between SelectedItem, SelectedValue and SelectedValuePath
... collection of Category objects (with each Category object having Name and ID properties). eg. ObservableCollection<Category>. The SelectedItem property will return you the currently selected Category object. For binding purposes however, this is not always what you want, as this only enable...
How to make input type= file Should accept only pdf and xls
...nspector. So in either case you need to check the file type on the server side (your second question).
Example:
<input type="file" name="upload" accept="application/pdf,application/vnd.ms-excel" />
To your third question "And when I click the files (PDF/XLS) on webpage it automatically sho...
How to create composite primary key in SQL Server 2008
...
CREATE TABLE UserGroup
(
[User_Id] INT NOT NULL,
[Group_Id] INT NOT NULL
CONSTRAINT PK_UserGroup PRIMARY KEY NONCLUSTERED ([User_Id], [Group_Id])
)
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ASP.NET MVC A potentially dangerous Request.Form value was detected from the client when using a cus
...t; }
On the controller action add this attribute to allow all HTML
[ValidateInput(false)]
public ActionResult SomeAction(MyViewModel myViewModel)
Brute force in web.config - definitely not recommended
In the web.config file, within the tags, insert the httpRuntime element with the attribute ...