Oracle database. How to update selected columns.

Question

the problem is:

I have two tables(column names are in brackets): Cars (CarColorId, CarName), CarColor (CarColorId, CarColorName);

The task is to UPDATE Cars.CarName with a string "_updated" but only if CarColor.CarColorName = 'red'. I have know idea how to do this without joins

I have tried this way:

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

CarColorId = 1 = red; This request works, but the task is to use both tables

Answer 1

You can try any one of this in Oracle

Normal Update

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');

Using Inline View (If it is considered updateable by Oracle)

Note : If you face a non key preserved row error add an index to resolve the same to make it update-able

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;

Using Merge

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

You can modify your query like this:

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

Answer 3

I know you said that you did not know how to do this without any joins. I don't know if that means you would prefer to avoid joins or whether you would be open to the possibility of using them if you could. If the latter is the case then check out this piece of code:

    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';

Hope this helps also.

T