ORACLE數據庫對比表結構

有時候會有某種需求：需要對比兩個表的表結構是否一致，有時候甚至是整個數據庫所有表的表結構對比......。表結構對比無非就是字段名、字段類型、字段數據類型、以及字段的順序的對比。如果需要對比表結構，可以通過下面簡單的腳本實現：

SELECT M.OWNER
      ,M.TABLE_NAME
      ,M.COLUMN_ID
      ,M.COLUMN_NAME
      ,M.DATA_TYPE
      ,M.DATA_LENGTH
      ,N.OWNER
      ,N.TABLE_NAME
      ,N.COLUMN_ID
      ,N.COLUMN_NAME
      ,N.DATA_TYPE
      ,N.DATA_LENGTH
FROM
(
SELECT OWNER
      ,TABLE_NAME
      ,COLUMN_ID
      ,COLUMN_NAME
      ,DATA_TYPE
      ,DATA_LENGTH
FROM DBA_TAB_COLUMNS
WHERE OWNER=&OWNER_A
  AND TABLE_NAME=&TABLE_NAME_A
) M LEFT JOIN
(
SELECT OWNER
      ,TABLE_NAME
      ,COLUMN_ID
      ,COLUMN_NAME
      ,DATA_TYPE
      ,DATA_LENGTH
FROM DBA_TAB_COLUMNS
WHERE OWNER=&OWNER_B
  AND TABLE_NAME=&TABLE_NAME_B
) N ON  M.COLUMN_ID =N.COLUMN_ID
    AND M.COLUMN_NAME = N.COLUMN_NAME
    AND M.DATA_TYPE = N.DATA_TYPE
    AND M.DATA_LENGTH= N.DATA_LENGTH
ORDER BY M.TABLE_NAME, M.COLUMN_ID;

但是如果A表與B表前面的字段一致，然而B表有一些額外的字段，那么上面的SQL（左連接）就會查不出兩者之間結構的不同。此時需要使用右連接才能對比出真正的表結構。所以如果需要對比兩者的表結構是否一致，最好左連接查一次，右連接查一次。才能真正的確認兩者的表結構的異同。

SELECT M.OWNER
      ,M.TABLE_NAME
      ,M.COLUMN_ID
      ,M.COLUMN_NAME
      ,M.DATA_TYPE
      ,M.DATA_LENGTH
      ,N.OWNER
      ,N.TABLE_NAME
      ,N.COLUMN_ID
      ,N.COLUMN_NAME
      ,N.DATA_TYPE
      ,N.DATA_LENGTH
FROM
(
SELECT OWNER
      ,TABLE_NAME
      ,COLUMN_ID
      ,COLUMN_NAME
      ,DATA_TYPE
      ,DATA_LENGTH
FROM DBA_TAB_COLUMNS
WHERE OWNER=&OWNER_A
  AND TABLE_NAME=&TABLE_NAME_A
) M RIGHT JOIN
(
SELECT OWNER
      ,TABLE_NAME
      ,COLUMN_ID
      ,COLUMN_NAME
      ,DATA_TYPE
      ,DATA_LENGTH
FROM DBA_TAB_COLUMNS
WHERE OWNER=&OWNER_B
  AND TABLE_NAME=&TABLE_NAME_B
) N ON  M.COLUMN_ID =N.COLUMN_ID
    AND M.COLUMN_NAME = N.COLUMN_NAME
    AND M.DATA_TYPE = N.DATA_TYPE
    AND M.DATA_LENGTH= N.DATA_LENGTH
ORDER BY M.TABLE_NAME, M.COLUMN_ID;