Перевести из ms sql server в oracle

DECLARE 
    pDishId NUMBER:="номер без кавычек!!!";
    fmt     VARCHAR2(10) :='ww';
    pBaseDate DATE := TRUNC(SYSDATE);
    id0     NUMBER := NULL;
BEGIN
FOR vv IN (
SELECT id FROM (
SELECT idDish id, ROW_NUMBER() OVER (ORDER BY cnt DESC) nn
FROM (
SELECT w.idDish, SUM(w.numberr) cnt
FROM Zakaz z,
WhatToZakaz w,
WhatToZakaz b
WHERE w.idZakaz = z.idZakaz
AND b.idZakaz = z.idZakaz
AND w.idDish <> pDishId
AND b.iddish = pDishId
AND TRUNC(z.date1, ''''||fmt||'''') = TRUNC(pBaseDate, ''''||fmt||'''')
GROUP BY w.idDish
)) WHERE nn=1)
LOOP
id0 := vv.id;
END LOOP;
dbms_output.put_line('vDishId='||id0);--отладка
END;

CREATE TABLE  "ZAKAZ" 
   (    "IDZAKAZ" NUMBER, 
    "IDVISITORS" NUMBER NOT NULL ENABLE, 
    "DATA" TIMESTAMP (6) WITH LOCAL TIME ZONE, 
    "IDSTUFF" NUMBER, 
    "TOTAL" NUMBER, 
     CONSTRAINT "ZAKAZ_CON" PRIMARY KEY ("IDZAKAZ") ENABLE
   )
/
ALTER TABLE  "ZAKAZ" ADD CONSTRAINT "ZAKAZ_CON1" FOREIGN KEY ("IDVISITORS")
      REFERENCES  "VISITORS" ("IDVISITORS") ENABLE
/
ALTER TABLE  "ZAKAZ" ADD CONSTRAINT "ZAKAZ_CON2" FOREIGN KEY ("IDSTUFF")
      REFERENCES  "STUFF" ("IDSTUFF") ENABLE
/
 
CREATE OR REPLACE TRIGGER  "BI_ZAKAZ" 
  before INSERT ON "ZAKAZ"               
  FOR each ROW  
BEGIN   
  IF :NEW."IDZAKAZ" IS NULL THEN 
    SELECT "ZAKAZ_SEQ".NEXTVAL INTO :NEW."IDZAKAZ" FROM sys.dual; 
  END IF; 
END; 
 
/
ALTER TRIGGER  "BI_ZAKAZ" ENABLE
/

DECLARE 
pDishId NUMBER:=1;
fmt VARCHAR2(10) :='ww';
pBaseDate DATE := TRUNC(SYSDATE);
id0 NUMBER := NULL;
BEGIN
FOR vv IN (
SELECT id FROM (
SELECT idDish id, ROW_NUMBER() OVER (ORDER BY cnt DESC) nn
FROM (
SELECT w.idDish, SUM(w.numberr) cnt
FROM Zakaz z,
WhatToZakaz w,
WhatToZakaz b
WHERE w.idZakaz = z.idZakaz
AND b.idZakaz = z.idZakaz
AND w.idDish <> pDishId
AND b.iddish = pDishId
AND TRUNC(z.data, ''''||fmt||'''') = TRUNC(pBaseDate, ''''||fmt||'''')
GROUP BY w.idDish
)) WHERE nn=1)
LOOP
id0 := vv.id;
END LOOP;
dbms_output.put_line('vDishId='||id0);--отладка
END;