want to replace several updates with just one

See more:

SQL-Server-2008R2

hi to all

i have a gridview where i show a schedule

first column is the iduser the following are the days, starting at day 1 of a month

what i want is to set the holidays days in the schedule

here is the sql code that i have

DECLARE @Date_Start AS DATETIME 
DECLARE @Schedule TABLE(Idx NUMERIC IDENTITY(1,1) PRIMARY KEY, IdUser NVARCHAR(20), D01 CHAR(14), D02 CHAR(14), D03 CHAR(14), D04 CHAR(14), D05 CHAR(14), UNIQUE(IdUser)) 
DECLARE @Holidays TABLE(Idx NUMERIC IDENTITY(1,1) PRIMARY KEY NOT NULL, Holiday DATETIME NOT NULL, UNIQUE(Holiday)) 

SET @Date_Start = CAST('2014-01-01 00:00:00.000' AS DATETIME) 

INSERT INTO @Schedule VALUES('0708', 'day 1', 'day 2', 'day 3', 'day 4', 'day 5') 
INSERT INTO @Schedule VALUES('0899', 'day 1', 'day 2', 'day 3', 'day 4', 'day 5') 
INSERT INTO @Schedule VALUES('0933', 'day 1', 'day 2', 'day 3', 'day 4', 'day 5') 
INSERT INTO @Schedule VALUES('1097', 'day 1', 'day 2', 'day 3', 'day 4', 'day 5') 
INSERT INTO @Schedule VALUES('1126', 'day 1', 'day 2', 'day 3', 'day 4', 'day 5') 
INSERT INTO @Schedule VALUES('1513', 'day 1', 'day 2', 'day 3', 'day 4', 'day 5') 

INSERT INTO @Holidays VALUES(CAST('2014-01-02 00:00:00.000' AS DATETIME)) 
INSERT INTO @Holidays VALUES(CAST('2014-01-04 00:00:00.000' AS DATETIME)) 


--UPDATE X SET X.[D01] = 'Holiday' FROM @Schedule X, @Holidays Y WHERE DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '0' 
--UPDATE X SET X.[D02] = 'Holiday' FROM @Schedule X, @Holidays Y WHERE DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '1' 
--UPDATE X SET X.[D03] = 'Holiday' FROM @Schedule X, @Holidays Y WHERE DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '2' 
--UPDATE X SET X.[D04] = 'Holiday' FROM @Schedule X, @Holidays Y WHERE DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '3' 
--UPDATE X SET X.[D05] = 'Holiday' FROM @Schedule X, @Holidays Y WHERE DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '4' 


UPDATE X 
SET [D01] = CASE WHEN DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '0' THEN 'Holiday' ELSE [D01] END, 
[D02] = CASE WHEN DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '1' THEN 'Holiday' ELSE [D02] END, 
[D03] = CASE WHEN DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '2' THEN 'Holiday' ELSE [D03] END, 
[D04] = CASE WHEN DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '3' THEN 'Holiday' ELSE [D04] END, 
[D05] = CASE WHEN DATEDIFF(dd, @Date_Start, Y.[Holiday]) = '4' THEN 'Holiday' ELSE [D05] END 
FROM @Schedule X INNER JOIN @Holidays Y ON Y.Idx IN ('1', '2') 

SELECT * FROM @Schedule 
SELECT * FROM @Holidays 

the commented updates do what i want

the non commented is the result of my web search, but i don't understand this format of update

the "ON" part is my last experience trying to understand how it works... but i don't get it

some help on this would be nice or a diffrent way

thanks for the time and replys