Question

问题是：

我有两个表（列名在括号中）：汽车（CarColorId，CarName），CarColor（CarColorId，CarColorName）;

任务是使用字符串“_updated”更新Cars.CarName，但仅限于CarColor.CarColorName ='red'。我知道如何在没有连接的情况下执行此操作

我试过这种方式：

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

CarColorId = 1 =红色; 此请求有效，但任务是使用两个表

Answer 1

您可以在Oracle中尝试其中任何一项

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');

使用内嵌视图（如果Oracle认为可以更新）

注意：如果您遇到非密钥保留行错误，请添加索引以解析相同内容以使其可更新

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

您可以像这样修改您的查询：

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

Answer 3

我知道你说你不知道如何在没有任何联接的情况下这样做。我不知道这是否意味着您更愿意避免加入，或者如果可以的话，您是否愿意使用它们。如果是后者，那么请查看这段代码：

    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';

希望这也有帮助。

Ť

Oracle数据库。如何更新选定的列。

3 个答案: