Question

what are the criteria which determine whether base table updation are possible through view or not​

Answer 1

Explanation:

The SQL UPDATE VIEW command can be used to modify the data of a view.

All views are not updatable. So, UPDATE command is not applicable to all views. An updatable view is one which allows performing a UPDATE command on itself without affecting any other table.

Contents:

When can a view be updated?

Syntax & Parameters

Example

SQL updatable views

SQL updatable views using IN operator

SQL updatable views with aggregate function

SQL update views with arithmetic expression

SQL update views using subqueries

When can a view be updated?

1. The view is defined based on one and only one table.

2. The view must include the PRIMARY KEY of the table based upon which the view has been created.

3. The view should not have any field made out of aggregate functions.

4. The view must not have any DISTINCT clause in its definition.

5. The view must not have any GROUP BY or HAVING clause in its definition.

6. The view must not have any SUBQUERIES in its definitions.

7. If the view you want to update is based upon another view, the later should be updatable.

8. Any of the selected output fields (of the view) must not use constants, strings or value expressions.

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