SELECT A, B,
SUBSTRING((SELECT ', ' + SalePointCode FROM Table2 T2 WHERE T1.ID = T2.ID FOR XML PATH ('')), 3, 8000) AS SPC
FROM Table1 T1

CREATE User dbo IDENTIFIED EXTERNALLY;

alter user dbo identified by 12345678

alter user dbo grant connect THROUGH X WITH ROLE Y;

UPDATE Table1
Set Field1 = T2.Field1
FROM Table1 T1 INNER JOIN Table2 T2 ON T1.ID = T2.ID
    LEFT JOIN Table3 T3 ON ...
WHERE ... (здесь условия для фильтра данных)

UPDATE (SELECT T1.Field1, T2.Field1 X
    FROM Table1 T1 INNER JOIN Table2 T2 ON T1.ID = T2.ID
        LEFT JOIN Table3 T3 ON ...
    WHERE ... )
SET Field1 = X

UPDATE Table1 T
SET Field1 = (SELECT T2.Field1
    FROM Table1 T1 INNER JOIN Table2 T2 ON T1.ID = T2.ID
        LEFT JOIN Table3 T3 ON ...
   WHERE ... )
WHERE EXISTS (SELECT T2.Field1
    FROM Table1 T1 INNER JOIN Table2 T2 ON T1.ID = T2.ID
        LEFT JOIN Table3 T3 ON ...
   WHERE ... )

MERGE INTO person p
   USING (   SELECT tabn, name, age FROM person1) p1
   ON (p.tabn = p1.tabn)
   WHEN MATCHED THEN UPDATE SET p.age = p1.age     
     DELETE WHERE (p1.tabn = 18)
   WHEN NOT MATCHED THEN INSERT (p.tabn, p.name, p.age)
    VALUES (p1.tabn, p1.name, p1.age)

MERGE INTO Тут_название_таблицы T USING
(SELECT ...
FROM ...
WHERE ...) U ON (тут условие)
WHEN MATCHED THEN 
  DELETE WHERE (а здесь условие удаления записи);

MERGE INTO Тут_название_таблицы T USING
(SELECT ...
FROM ...
WHERE ...) U ON (тут условие)
WHEN MATCHED THEN UPDATE SET T.Любое_поле = T.Любое_поле
  DELETE WHERE (а здесь условие удаления записи);