- What are after triggers?
- Can we use DML in view?
- What is difference between view and materialized view?
- How many types of views are there in Oracle?
- How do you change the view?
- How can we insert data into a view?
- Are views stored in database?
- Can we update the view in SQL Server?
- What is instead of trigger?
- Can we insert update delete in view in SQL?
- What is true about updates through a view?
- What is the syntax to rename view?
- Why view is used in SQL?
- How do I change the view in SQL?
- Does updating a view update the table?
- What is difference between table and view?
- Can we update view in Oracle?
- Are views updatable?
What are after triggers?
Before triggers: used to update or validate record values before they’re saved to the database.
After triggers: used to access field values that are set by the system (such as a record’s Id or LastModifiedDate field) and to effect changes in other records.
The records that fire the after the trigger is read-only..
Can we use DML in view?
A view can be defined as a virtual table or a stored query and the data accessible through a view is not stored in the database as a distinct object. … However, views can be used and perform DML operations ( Insert , Update & Delete ) also.
What is difference between view and materialized view?
A view uses a query to pull data from the underlying tables. A materialized view is a table on disk that contains the result set of a query. Materialized views are primarily used to increase application performance when it isn’t feasible or desirable to use a standard view with indexes applied to it.
How many types of views are there in Oracle?
2 typesThe table on which a View is based are called BASE Tables. There are 2 types of Views in SQL: Simple View and Complex View. Simple views can only contain a single base table.
How do you change the view?
The ALTER VIEW command allows you to modify a view. A view is based on the result set from a query consisting of a SELECT statement or a UNION of two or more SELECT statements. See CREATE VIEW for further information on using a UNION.
How can we insert data into a view?
‘100000.00’; To explain the INSERT INTO statement, I’m simply using SELECT after the name of our view, which is a very simple way to insert data into tables as we’re inserting new data based on the result of the SELECT statement. As can be seen, we can do data modifications through views.
Are views stored in database?
A view is a virtual table whose contents are defined by a query. Like a table, a view consists of a set of named columns and rows of data. Unless indexed, a view does not exist as a stored set of data values in a database.
Can we update the view in SQL Server?
The SQL UPDATE VIEW command can be used to modify the data of a view. All views are not updatable. … An updatable view is one which allows performing a UPDATE command on itself without affecting any other table.
What is instead of trigger?
What is an INSTEAD OF trigger. An INSTEAD OF trigger is a trigger that allows you to skip an INSERT , DELETE , or UPDATE statement to a table or a view and execute other statements defined in the trigger instead. … In other words, an INSTEAD OF trigger skips a DML statement and execute other statements.
Can we insert update delete in view in SQL?
You can insert, update, and delete rows in a view, subject to the following limitations: If the view contains joins between multiple tables, you can only insert and update one table in the view, and you can’t delete rows. You can’t directly modify data in views based on union queries.
What is true about updates through a view?
What is true about updates through a view? When you update a view only the constraints on the underlying table will be in effect. theunderlying tables. When you update a view group functions are automatically computed.
What is the syntax to rename view?
MySQL Rename View RENAME TABLE original_view_name TO new_view_name; In this syntax: First, specify the name of the view that you want to rename after the RENAME TABLE keywords. Then, specify the new name of the view after the TO keyword.
Why view is used in SQL?
Views are used for security purposes because they provide encapsulation of the name of the table. Data is in the virtual table, not stored permanently. Views display only selected data. We can also use Sql Join s in the Select statement in deriving the data for the view.
How do I change the view in SQL?
To modify a viewIn Object Explorer, click the plus sign next to the database where your view is located and then click the plus sign next to the Views folder.Right-click on the view you wish to modify and select Design.More items…•
Does updating a view update the table?
Yes, when you update a view it affects original table, because SELECT opens an implicit cursor which points to the records from the base table. When ever you update the records it updates the original data since they are pointers to the original.
What is difference between table and view?
A view is a virtual table. A view consists of rows and columns just like a table. The difference between a view and a table is that views are definitions built on top of other tables (or views), and do not hold data themselves. If data is changing in the underlying table, the same change is reflected in the view.
Can we update view in Oracle?
Answer: A VIEW in Oracle is created by joining one or more tables. When you update record(s) in a VIEW, it updates the records in the underlying tables that make up the View. So, yes, you can update the data in an Oracle VIEW providing you have the proper privileges to the underlying Oracle tables.
Are views updatable?
A view behaves like a table because you can query data from it. However, you cannot always manipulate data via views. A view is updatable if the statement against the view can be translated into the corresponding statement against the underlying table.