1  BEGIN
  2  MERGE INTO merge1 m1
  3      USING (SELECT a,b,c FROM merge) e
  4      ON (m1.a = e.a)
  5      WHEN MATCHED THEN
  6     delete where m1.c = e.c
  7      WHEN NOT MATCHED THEN
  8        INSERT (m1.a, m1.b)
  9        VALUES (e.a, e.b);
 10  DBMS_OUTPUT.PUT_LINE(TO_CHAR(SQL%ROWCOUNT) || ' rows merged.');
 11* END;
SQL> /
   delete where m1.c = e.c
   *
ERROR at line 6:
ORA-06550: line 6, column 4:
PL/SQL: ORA-00905: missing keyword
ORA-06550: line 2, column 1:
PL/SQL: SQL Statement ignored

BEGIN
MERGE INTO merge1 m1
    USING (SELECT a,b,c FROM merge) e
    ON (m1.a = e.a)
    WHEN MATCHED THEN 
   delete 
    WHEN NOT MATCHED THEN
      INSERT (m1.a, m1.b)
      VALUES (e.a, e.b);
DBMS_OUTPUT.PUT_LINE(TO_CHAR(SQL%ROWCOUNT) || ' rows merged.');
END;