Suppose I have a view created on a table. If I change some record on my view, the original table is also changed too. What if I join this view with an another table and change some records on this result table I got by joining, would original table on which view based also be changed?
In principle, yes, if the views are constructed in such a way that the underlying tables are updateable through the view. For example, let's say I have a table named TABLE_1 and create a view VIEW_1 as follows:
CREATE OR REPLACE VIEW VIEW_1 AS
SELECT *
FROM TABLE_1
If I issue the update statement
UPDATE VIEW_1
SET FIELD_N = 'XYZ'
WHERE KEY_1 = 123
Oracle is bright enough to pass the UPDATE through to the underlying table, and TABLE_1 will be updated.
A view of any complexity, however, will most likely contain operations that make the view non-updateable. So let's say I have the following VIEW_2:
CREATE OR REPLACE VIEW VIEW_2 AS
SELECT KEY_1,
FIELD_N,
SUM(SOME_OTHER_FIELD) AS OTHER_SUM,
MIN(YADDA_YADDA) AS MIN_YADDA
FROM TABLE_1
GROUP BY KEY_1,
FIELD_N
an UPDATE of this view will fail with an ORA-01732: data manipulation operation not legal on this view error. So whether you can update through a view or not very much depends on what operations the view is performing.