Oracle数据库。 如何更新选定的列。

Question

问题是：

我有两个表（列名放在方括号中）：汽车（CarColorId，CarName），CarColor（CarColorId，CarColorName）；

任务是使用字符串“ _updated”更新Cars.CarName，但前提是CarColor.CarColorName ='red'。 我知道想法如何不加入联接

我已经尝试过这种方式：

UPDATE Cars set CarName = concat (CarName, '_updated') WHERE CarColorId = 1;

CarColorId = 1 =红色； 该请求有效，但任务是使用两个表

Answer 1

您可以在Oracle中尝试任何一种

正常更新

UPDATE
      CARS
SET
      CARS.CARNAME =
          CONCAT ( CARS.CARNAME,
                 '_updated' )
WHERE
      EXISTS
          (SELECT
                CARCOLOR.CARCOLORID
           FROM
                CARCOLOR
           WHERE
                CARS.CARCOLORID = CARCOLOR.CARCOLORID
                AND CARCOLOR.CARCOLORNAME = 'RED');

使用内联视图（如果Oracle认为可更新）

注意 ：如果遇到非键保留行错误，请添加索引以解决该错误，使其可更新

UPDATE
      (SELECT
            CARS.CARNAME AS OLD,
            CONCAT ( CARS.CARNAME,
                    '_updated' )
                AS NEW
       FROM
                CARS
            INNER JOIN
                CARCOLOR
            ON CARS.CARCOLORID = CARCOLOR.CARCOLORID
       WHERE
            CARCOLOR.CARCOLORNAME = 'RED') T
SET
      T.OLD     = T.NEW;

使用合并

MERGE INTO
      CARS
USING
      (SELECT
            CARS.ROWID AS RID
       FROM
                CARS
            INNER JOIN
                CARCOLOR
            ON CARS.CARCOLORID = CARCOLOR.CARCOLORID
       WHERE
            CARCOLOR.CARCOLORNAME = 'RED')
ON
      ( ROWID = RID )
WHEN MATCHED
THEN
    UPDATE SET CARS.CARNAME =
                 CONCAT ( CARS.CARNAME,
                        '_updated' );

Answer 2

您可以像这样修改查询：

UPDATE
  Cars
set
  CarName = concat (CarName, '_updated')
WHERE
  CarColorId in (
    select
      CarColorId
    from
      CarColor
    where
      CarColorName='red'
  )
;

Answer 3

我知道您说过，如果没有任何加入，您将不知道该如何做。 我不知道这是否意味着您希望避免联接，或者是否愿意使用联接。 如果是后者，请查看以下代码：

    UPDATE
    (
          SELECT c.CarName, cc.CarColorName
            FROM Cars c
      INNER JOIN CarColors cc
              ON c.CarColorId = cc.CarColorId
    ) CarsWithColor
    SET CarsWithColor.CarName = CarsWithColor.CarName || '_Updated' 
    WHERE CarsWithColor.CarColorName = 'red';

希望这也会有所帮助。

Ť