java - Insert only if row doesn't exist -


i using preparedstatement prepare sql queries. want insert row in table if , if doesn't exist.

i tried -

insert users (userid) values (?) on duplicate key update userid = ?

but unnecessarily update userid.

how can insert userid here ? 

insert  users          (userid)  select  ?   not exists         (         select  *             users            userid = ?         )

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