Oracle creates a primary key from growth ____oracle

Create a sequence first

CreateSequence testincrease_sequence
IncrementBy 1--each time you add
a few startwith 1--start counting from 1
nomaxvalue--do not set the maximum value, To set the maximum value: maxvalue9999
nocycle--has been accumulated, does not cycle

Note that the pl/sql is created in the trigger, and can not immediately get the sq sequence, need to exit again to re-enter on it, the truth of which I am not very clear

And then create the trigger

Create or replace trigger MER_ONECODEPAYMENT_TRG
  before insert on
  merchant_onecodepayment_info for each 
  Row
declare
  --local variables here
begin
  Select Mer_onecodepayment_seq.nextval into:New.id from Dual;
End MER_ONECODEPAYMENT_TRG;