Sybase 12.4.2 manual Modifying views, Permissions on views, An existing view definition, 130

Working with views

Inserting and deleting on views

CREATE VIEW viewname AS

UPDATE, INSERT, and DELETE statements are allowed on some views, but not on others, depending on their associated SELECT statement.

You cannot update, insert into or delete from views in the following cases:

•Views containing aggregate functions, such as COUNT(*)

•Views containing a GROUP BY clause in the SELECT statement

•Views containing a UNION operation

In all these cases, there is no way to translate the UPDATE, INSERT, or DELETE into an action on the underlying tables.

Modifying views

	You can modify a view using the ALTER VIEW statement. The ALTER VIEW
	statement replaces a view definition with a new definition; it does not modify
	an existing view definition.
	The ALTER VIEW statement maintains the permissions on the view.
Example	For example, to replace the column names with more informative names in the
	DepartmentSize view described above, you could use the following statement:
	ALTER VIEW DepartmentSize
	(Dept_ID, NumEmployees)
	AS
	SELECT dept_ID, count(*)
	FROM Employee
	GROUP BY dept_ID

Permissions on views

A user may perform an operation through a view if one or more of the following are true:

•The appropriate permission(s) on the view for the operation has been granted to the user by a DBA.

•The user has the appropriate permission(s) on all the base table(s) for the operation.

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