如何删除数据库中的冗余数据（翻译）

如何删除数据库中的冗余数据（翻译） (9) CREATE OR REPLACE PROCEDURE DeleteDuplicates(
   pCommitBatchSize IN INTEGER := 5000) IS

CURSOR CSr_Duplicates IS
   SELECT ID, LastName, FirstName
   FROM Customers
   WHERE (LastName, FirstName) IN
   (SELECT LastName, FirstName
       FROM Customers
       GROUP BY LastName, FirstName
       HAVING COUNT(*) > 1)
   ORDER BY LastName, FirstName;

／＊保存上一次的姓和名＊／
vLastName Customers.LastName%TYPE := NULL;
vFirstName Customers.FirstName%TYPE := NULL;

vCounter INTEGER := 0;

BEGIN

   FOR vDuplicates IN csr_Duplicates
   LOOP
      IF vLastName IS NULL OR
      (vDuplicates.LastName != vLastName
       OR NVL(vDuplicates.FirstName, ' ') != NVL(vFirstName, ' '))
 THEN
 ／＊第一次取出行或者是一个新行
  保存它的姓和名的值＊／
    vLastName := vDuplicates.LastName;
    vFirstName := vDuplicates.FirstName;

 ELSE
       ／＊冗余数据，删除它＊／
    DELETE
            FROM Customers
       WHERE ID = vDuplicates.ID;

    vCounter := vCounter + 1;

／＊提交结果＊／
    /* Commit every pCommitBatchSize rows */
    IF MOD(vCounter, pCommitBatchSize) = 0
    THEN
       COMMIT;
    END IF;

      END IF;
   END LOOP;

   IF vCounter > 0
   THEN
      COMMIT;
   END IF;