Try following query:
UPDATE TableB
SET [1] = ISNULL(z.[1],TableB.[1]),
[2] = ISNULL(z.[2],TableB.[2]),
[3] = ISNULL(z.[3],TableB.[3]),
[4] = ISNULL(z.[4],TableB.[4]),
[5] = ISNULL(z.[5],TableB.[5]),
[6] = ISNULL(z.[6],TableB.[6]),
[7] = ISNULL(z.[7],TableB.[7])
FROM (
SELECT [1],[2],[3],[4],[5],[6],[7]
FROM (SELECT Id, Value
FROM TableA)AS p
PIVOT (MAX(Value) FOR Id IN([1],[2],[3],[4],[5],[6],[7]))AS pvt
)z
EDIT
In order to have dynamic pivot use following query:
DECLARE @columns1 NVARCHAR(1000) = '',
@columns2 NVARCHAR(1000) = '',
@sql NVARCHAR(MAX)
SELECT @Columns1 = STUFF((SELECT ',['+Value+'] = ISNULL(z.['+Value+'],TableB.['+Value+'])'
FROM (SELECT DISTINCT Value FROM TableA)z
FOR XML PATH('')),1,1,''),
@Columns2 = STUFF((SELECT ',['+Value+']'
FROM (SELECT DISTINCT Value FROM TableA)z
FOR XML PATH('')),1,1,'')
SET @sql="Update TableB
Set "+@columns1+'
From (
Select '+ @columns2+'
From (Select Id, Value From TableA) AS p
Pivot (MAX(Value) For Id IN ('+@columns2+')) AS Pvt
)z'
EXECUTE(@sql)
2
solved updating values in one table from another table using DYNAMIC SQL in MSSQL