mysql - SQL idea for a query -

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i have kind of table

id-----categoryid-----price  1---------1-----------200  2---------1-----------300  3---------2-----------150  4---------2-----------100

i need sql query can average of elements category id. results should like:

categoryid----------avg_price  1-------------------250  2-------------------175

i have not been able think through..

select categoryid, avg(price) table group categoryid

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