rest - What is meant by PUT method idempotent in RESTful web service? -

i trying decide http method should used put or post.

while looking @ posts on stackoverlflow see this post.

one of answers in post says

put idempotent, if put object twice, has no effect. nice property, use put when possible.

can 1 me out here example. lets have scenario trying create student entry passed in student table in rdbms.

so here if try put entry again , again there no effect?

in put, you're setting all values of resource, when put done, know state of resource. if wait week , call put again, still know state of resource.

a post, contrast, not idempotent - post subset of values. if call post today, wait week, , make same post call again, don't know state of resource - might have changed value you're not setting in post.

idempotent means no matter when or how make call, end state of resource same.

delete , idempotent.