Quick Answer: Which Type Of Select Statements Can Be Used To Construct A View?

Which is faster table or view?

MS SQL Indexed views are faster than a normal view or query but indexed views can not be used in a mirrored database invironment (MS SQL).

In this situation a temporary table using # or @ to hold your data to loop through is faster than a view or a query..

Why view is called virtual table?

A virtual table is an object that presents an SQL table interface but which is not stored in the database file, at least not directly. The virtual table mechanism is a feature of SQLite that allows SQLite to access and manipulate resources other than bits in the database file using the powerful SQL query language.

What view means?

noun. an instance of seeing or beholding; visual inspection. sight; vision. range of sight or vision: Several running deer came into the view of the hunters. a sight or prospect of a landscape, the sea, etc.: His apartment affords a view of the park.

How do you use a view?

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.

How can we insert data into a view Mcq?

How can we insert data into a view? Explanation: We can insert data into a view using the inset into values ( ); statement. This operation can be done only if the view is updatable. Explanation: We can update a view only if it has a single database relation in the “from” clause.

What is create view in SQL?

The CREATE VIEW command creates a view. A view is a virtual table based on the result set of an SQL statement.

How do you create a database view?

Creating a Database ViewEnter an explanatory short text in the field Short text. … In column Tables on the Tables/Join conditions tab page, define the tables you want to include in the view. … Link the tables with join conditions. … On the View fields tab page, select the fields that you want to copy to the view.More items…

Can we create a view without table?

A view can be created even if the defining query of the view cannot be executed. … For example, if a view refers to a non-existent table or an invalid column of an existing table or if the owner of the view does not have the required privileges, then the view can still be created and entered into the data dictionary.

Why view is used in SQL?

Views are virtual tables that can be a great way to optimize your database experience. Not only are views good for defining a table without using extra storage, but they also accelerate data analysis and can provide your data extra security.

Are MySQL views faster than queries?

A view is not compiled. Its a virtual table made up of other tables. When you create it, it doesn’t reside somewhere on your server. The underlying queries that make up the view are subject to the same performance gains or dings of the query optimizer.

Can view hold indexes?

The view is not “holding data”, it is holding a query. The query statement has constants in it that are turned into a result set that can be used by other queries. … These are views where you have indexes and the values are actually stored in the database. However, this is not an example of a materialized view.

What is difference between view and table?

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. … Space savings: Views takes very little space to store, since they do not store actual data.

How do you display in SQL?

The SQL SELECT StatementSELECT column1, column2, … FROM table_name;SELECT * FROM table_name;Example. SELECT CustomerName, City FROM Customers;Example. SELECT * FROM Customers;

Can we modify view in SQL?

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. You can’t modify data in views that use GROUP BY or DISTINCT statements. … There is no checking of view criteria.

How do you write a view?

The syntax for creating a view is as follows:CREATE VIEW “VIEW_NAME” AS “SQL Statement”;CREATE VIEW V_Customer. AS SELECT First_Name, Last_Name, Country. FROM Customer;CREATE VIEW V_REGION_SALES. AS SELECT A1.Region_Name REGION, SUM(A2.Sales) SALES. FROM Geography A1, Store_Information A2. … SELECT * FROM V_REGION_SALES;

How do I create a view from another view?

2 Answers. You can certainly have a view that’s built on top of another view: create table my_table (id number, name varchar2(20), address varchar2(30)); table MY_TABLE created. create or replace view my_view_1 as select id, name from my_table; view MY_VIEW_1 created.

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.

What Cannot be done on a view?

What cannot be done on a view? Explanation: In MySQL, ‘Views’ act as virtual tables. It is not possible to create indexes on a view. However, they can be used for the views that are processed using the merge algorithm.