用其它的 Table 來更新資料(Update From table)

pl-sql

UPDATE table1 a
SET table1_column = (SELECT table2_column
FROM table2
WHERE ID = a.ID)

如果雙方均有KEY值，使用下面這個方法會超快

UPDATE (
  SELECT PAYCDL.ID_NO, PAYCDL.DATE_ADD DATE_ADD_OLD,PAYCDL.DATE_LAST_MAINT DATE_LAST_MAINT_OLD,
               EXSCCS_PMS2.DATE_ADD DATE_ADD_NEW, EXSCCS_PMS2.DATE_LAST_MAINT DATE_LAST_MAINT_NEW
          FROM PAYCDL,
               EXSCCS_PMS2
         WHERE PAYCDL.ID_NO = EXSCCS_PMS2.ID_NO)
   SET DATE_ADD_OLD = DATE_ADD_NEW,
       DATE_LAST_MAINT_OLD = DATE_LAST_MAINT_NEW

-----------------------------------
ms-sql

UPDATE table1
      SET table1.col = table2.col1
FROM table2 WHERE table2.oldCol = table1.col