diff --git a/README.md b/README.md index 824a525..a65c11c 100644 --- a/README.md +++ b/README.md @@ -784,7 +784,8 @@ The following guidelines indicate when the use of an index should be reconsidere - A view is actually a composition of a table in the form of a predefined SQL query. - A view can contain all rows of a table or select rows from a table. - A view can be created from one or many tables which depends on the written SQL query to create a view. -- Views, which are a type of virtual tables allow users to do the following − +- +Views, which are a type of virtual tables allow users to do the following − **- Structure data in a way that users or classes of users find natural or intuitive.** @@ -813,4 +814,24 @@ The following guidelines indicate when the use of an index should be reconsidere ## Updating a View -- +A view can be updated under certain conditions which are given below − + +**- The SELECT clause may not contain the keyword DISTINCT. + +The SELECT clause may not contain summary functions. + +The SELECT clause may not contain set functions. + +The SELECT clause may not contain set operators. + +The SELECT clause may not contain an ORDER BY clause. + +The FROM clause may not contain multiple tables. + +The WHERE clause may not contain subqueries. + +The query may not contain GROUP BY or HAVING. + +Calculated columns may not be updated. + +All NOT NULL columns from the base table must be included in the view in order for the INSERT query to function.