Thursday, April 18, 2013

Modifying Data in Tables through a View in SQL Server

Can we modify the table data through SQL View? 

The answer is: Yes !

We can modify the data of an underlying base table through a view, in the same manner as we modify data in a table by using UPDATE, INSERT and DELETE statements or by using the BCP utility and BULK INSERT statement. However, the following restrictions apply to updating views, but do not apply to tables:

·         Any modifications, including UPDATE, INSERT, and DELETE statements, must reference columns from only one base table.

·         The columns that are being modified in the view must reference the underlying data in the table columns directly. They cannot be derived in any other way, such as through:

1.       An aggregate function (AVG, COUNT, SUM, MIN, MAX, GROUPING, STDEV, STDEVP, VAR and VARP).

2.       A computation; the column cannot be computed from an expression using other columns. Columns formed using set operators (UNION, UNION ALL, CROSSJOIN, EXCEPT, and INTERSECT) amount to a computation and are also not updatable.

·         The columns that are being modified cannot be affected by GROUP BY, HAVING, or DISTINCT clauses.

·         TOP cannot be used anywhere in the select_statement of the view when WITH CHECK OPTION is also specified.

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