What Query for some issue ?

[Andrzej]

Thanks a lot.
There are very usefull links. Unfortunately I'm not able to rate your perfect post.

by the way
please find answer below for my issue

USE ABBMeasureHistory

SELECT T1.X,
SUM(CASE T2.Sensor WHEN 4 THEN T2.Val ELSE 0 END) AS Sensor4,
SUM(CASE T2.Sensor WHEN 5 THEN T2.Val ELSE 0 END) AS Sensor5,
SUM(CASE T2.Sensor WHEN 6 THEN T2.Val ELSE 0 END) AS Sensor6,
SUM(CASE T2.Sensor WHEN 7 THEN T2.Val ELSE 0 END) AS Sensor7
FROM Table_1 T1, Table_2 T2
WHERE T1.id_t1 = T2.id_t1 AND T1.id_t1=1001
GROUP BY T1.X
GO

The more I learn SQL the more I am impressed by SQL.