oracle身份证18转15

CREATE OR REPLACE FUNCTION GET_OLDCERT(
    NEWCERT IN VARCHAR2)
  RETURN VARCHAR2
IS
  OLD_CERT VARCHAR2(15);
BEGIN
  OLD_CERT:=SUBSTR(NEWCERT,1,6)||SUBSTR(NEWCERT,9,9);
  RETURN OLD_CERT;
END GET_OLDCERT;