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SQL Server indexes - ascending or descending, what difference does it make?
...e values of the pk. They are also ordered within each value of col1.
This means that that leaves of the index are actually ordered on (col1, pk), and this query:
SELECT col1, pk
FROM mytable
ORDER BY
col1, pk
needs no sorting.
If we create the index as following:
CREATE INDEX ix_my...
Primary key or Unique index?
...nique
A Unique value doesn't have to be the Representaion of the Element
Meaning?; Well a primary key is used to identify the element, if you have a "Person" you would like to have a Personal Identification Number ( SSN or such ) which is Primary to your Person.
On the other hand, the person migh...
XDocument or XmlDocument
...
Could you tell me why they are different ? I mean yeah XDocument looks pretty neat but as for DOM level difference, aren't they both xml, is there any scheme that shows both Microsoft X-DOM and W3C Compliant DOM ? Thanks.
– Tarik
O...
HTML input - name vs. id [duplicate]
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"Shares the same namespace" ... what is this supposed to mean? An id may have the same value as a name attribute (despite the requirement that an id be unique). Each attribute works as usual without conflict. This suggests that id and name attributes have separate namespaces.
...
What's the proper value for a checked attribute of an HTML checkbox?
...is is wrong. If you look at the spec, it says: checked (checked) which means "The checked attribute can have the value 'checked'). Only checked is an acceptable value, none of the others are. Boolean attributes allow you to omit everything except the value so checked is acceptable as well as che...
Insert, on duplicate update in PostgreSQL?
... in isolation or on a locked table, but is subject to race conditions that mean it might still fail with duplicate key error if a row is inserted concurrently, or might terminate with no row inserted when a row is deleted concurrently. A SERIALIZABLE transaction on PostgreSQL 9.1 or higher will hand...
List of lists changes reflected across sublists unexpectedly
...[[1] * 4] * 3
This is equivalent to:
lst1 = [1]*4
lst = [lst1]*3
This means lst is a list with 3 elements all pointing to lst1. This means the two following lines are equivalent:
lst[0][0] = 5
lst1[0] = 5
As lst[0] is nothing but lst1.
To obtain the desired behavior, you can use list compre...
Changing an element's ID with jQuery
...
What you mean to do is:
jQuery(this).prev("li").attr("id", "newID");
That will set the ID to the new ID
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How to drop a table if it exists?
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Fwiw -- The 'U' for the second param apparently means "Only look for objects with this name that are tables". One source. So OBJECT_ID('TableName') isn't wrong, but it's not insanely precise either, thus 'U' in @Martin's excellent answer.
– ruffin
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PHP Session Fixation / Hijacking
...ers.
Regenerate the session ID anytime the session's status changes. That means any of the following:
User authentication
Storing sensitive info in the session
Changing anything about the session
etc...
Session Hijacking
This is where an attacker gets a hold of a session identifier and is abl...