Though I would understand both in written and oral communication, I find the first to be pretty odd.
I wouldn't ever use it, and strongly prefer the second, "according to".
Why is this so odd?
I looked a bit in the OED at the use of "as per" (odd in itself for combining two prepositions).
It was first used in 1869 as a "slang" form "as per usual" by itself.
I did however come across an entry that has a similar meaning to what you're looking for here: "by".
By.
3.
a.
According to; as stated, indicated, or directed by, as per advice, per instructions, per invoice, per ledger, etc.
Usually preceded by as.
This was used as early as 1446 and as late as 1989.
The difference here, I think, has been touched on:
this meaning implies some obligation or requirement.
No other entries seem to come close, and this matches my own mental lexicon for "per" and "as per".
It just doesn't fit in this situation.
english.stackexchange.com/users/89/Charlie
The two phrases have the same meaning but different in register. "
According to" is normal register while "as per" connotes commercial correspondence as in: The shipment will arrive prior to December first, as per our agreement.
english.stackexchange.com/users/30/Edward Tanguay
Both are bad English and are unnatural and incorrect uses of English as they are superfluous and add no additional or necessary information to the sentence.
In general this type of mistake is common amongst Indian speakers of English.
I believe, quiet ironically, that it is thought to add an air of intelligence to a statement.
In fact, to a native speaker, it adds an air of pretentiousness that may serve to undermine the speaker in the eyes of the listener.
It clearly goes without saying that any statement you make is 'as per your knowledge' or 'according to your knowledge' unless stated otherwise.
What else could possibly be the case.
What is the difference for example, between these statements with and without this structure... A) "
Manchester United won the Premier League in 2012" B) "
According to my knowledge, Manchester United won the Premier League in 2012"orB) "
As per my knowledge, Manchester United won the Premier League in 2012"
In English we use 'according to...' to cite someone else.
To cite oneself is clearly absurd, unless you are citing a paper you published, or something you have formally written.
To cite your opinion or knowledge is meaningless.
We use 'as per' to refer back to something, such as 'as per our previous discussion' or 'as per the rules of the game'.
Again, to use it to refer back to your knowledge appears ridiculous.
Regards and best of luck Sanjay
english.stackexchange.com/users/53121/Sanjay
Per means according to , so you can in fact say "per our agreement, you must...".
The as in your first sentence is pleonastic, and sounds affected: I'd avoid it.
The very common "as per usual" is a humorous prolixity.
Whether to use per or according to is the same as whether to use any archaic form or common usage.
In some areas (e.g. law) it's more common to see per , so you could use it to set the tone as legalese.
english.stackexchange.com/users/2895/Mark
People who want to sound important write as per .
People who are important write according to .
english.stackexchange.com/users/12952/Barrie England
Just to clarify... '
As per' is often used in legal discussions, for example regarding contracts.
For example, "As per article 4 section 8..." and this has a different meaning to "According to article 4 section 8..." For example if Article 4 Section 8 stated that you needed a doctors note in order to take sick leave you might say...
As per Article 4 Section 8 of our contract, I have attached a copy of my doctors note.
whereas with according to the meaning would be different.
According to Article 4 Section 8 I must supply a sick note in order to take sick leave.
english.stackexchange.com/users/53121/Sanjay
I understand that per is an older and more formal version of according to , so it is very common to encounter per in some very serious and formal written language while according to has become a normal usage.
english.stackexchange.com/users/14543/Evelyn
See the following two sentences.   As per my knowledge it is right.   According to my knowledge it is right.    Are both the sentences right?  What is the difference and use of "as per" and "according to"?
What is the difference between "as per" and "according to"?
english.stackexchange.com
<grammaticality><differences>
english.stackexchange.com/questions/256
english.stackexchange.com/users/40/chanchal1987
It is possible that they both mean the same thing. However, there may be a difference in register, with "as per" being considered more formal. However, some people would claim that they are both poor English or at least have different meanings. It is possible that "according to" is used more to cite someone and "as per" is used to refer back to something. The more common form is 'according to' nowadays - 'as per' is not incorrect but it can sound pretentious or overly formal.
It is possible that they both mean the same thing. However, there may be a difference in register, with "as per" being considered more formal. However, some people would claim that they are both poor English or at least have different meanings. It is possible that "according to" is used more to cite someone and "as per" is used to refer back to something. Per  means  according to.  The two phrases have the same meaning but a different register. 'As per' is an older form and is often used in legal discussions, for example for contracts.
The two phrases have the same meaning but different in register.  "According to" is normal register while "as per" connotes commercial correspondence as in:   The shipment will arrive prior to December first, as per our agreement The main difference between these two sentences appears to be register, with "as per" being the more formal of the two. However, in the examples given, both would be considered poor English.
The more common form is 'according to' - but 'as per' is not incorrect. The two phrases mean the same but vary in register. Both are bad English and to be avoided. The correct form of 'as per' is actually 'per'. As per' is used by people who want to sound important. As per' is more often used in legal texts. As per' is an older form that has been replaced by 'according to'
The two phrases have the same meaning but a different register.  Per  means  according to.   S1: 'As per' is often used in legal discussions, for example for contracts. Per' is also an older and more formal version of  'according to'.
Both sentences would be considered quite odd and possibly poor English. The main difference between these two sentences is probably the register, with "as per" being more formal.