What is a View in Oracle

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What is a view in Oracle

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If you like the idea of Views  but are worried about performance you can get Oracle to create a cached table representing the view which oracle keeps up to date  See materialized views

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A View in Oracle and in other database systems is simply the representation of a SQL statement that is stored in memory so that it can easily be re-used  For example  if we frequently issue the following query  SELECT customerid  customername FROM customers WHERE countryid  US     To create a view use the CREATE VIEW command as seen in this example  CREATE VIEW view uscustomers AS SELECT customerid  customername FROM customers WHERE countryid  US     This command creates a new view called view uscustomers  Note that this command does not result in anything being actually stored in the database at all except for a data dictionary entry that defines this view  This means that every time you query this view  Oracle has to go out and execute the view and query the database data  We can query the view like this   SELECT   FROM view uscustomers WHERE customerid BETWEEN 100 AND 200    And Oracle will transform the query into this   SELECT    FROM  select customerid  customername from customers WHERE countryid  US    WHERE customerid BETWEEN 100 AND 200   Benefits of using Views   Commonality of code being used  Since a view is based on one common set of SQL  this means that when it is called it   s less likely to require parsing   Security  Views have long been used to hide the tables that actually contain the data you are querying  Also  views can be used to restrict the columns that a given user has access to  Predicate pushing   You can find advanced topics in this article about  How to Create and Manage Views in Oracle

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A view is simply any SELECT query that has been given a name and saved in the database  For this reason  a view is sometimes called a named query or a stored query  To create a view  you use the SQL syntax        CREATE OR REPLACE VIEW  lt view name gt  AS      SELECT  lt any valid select query gt

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regular view----- short name for a query no additional space is used here  Materialised view---- similar to creating table whose data will refresh periodically based on data query used for creating the view

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A view is a virtual table  which provides access to a subset of column from one or more table  A view can derive its data from one or more table  An output of query can be stored as a view  View act like small a table but it does not physically take any space  View is good way to present data in particular users from accessing the table directly  A view in oracle is nothing but a stored sql scripts  Views itself contain no data

User · Answer

If you like the idea of Views  but are worried about performance you can get Oracle to create a cached table representing the view which oracle keeps up to date  See materialized views

User · Answer

A view is a virtual table  which provides access to a subset of column from one or more table  A view can derive its data from one or more table  An output of query can be stored as a view  View act like small a table but it does not physically take any space  View is good way to present data in particular users from accessing the table directly  A view in oracle is nothing but a stored sql scripts  Views itself contain no data

User · Answer

A view is simply any SELECT query that has been given a name and saved in the database  For this reason  a view is sometimes called a named query or a stored query  To create a view  you use the SQL syntax        CREATE OR REPLACE VIEW  lt view name gt  AS      SELECT  lt any valid select query gt

User · Answer

A View in Oracle and in other database systems is simply the representation of a SQL statement that is stored in memory so that it can easily be re-used  For example  if we frequently issue the following query  SELECT customerid  customername FROM customers WHERE countryid  US     To create a view use the CREATE VIEW command as seen in this example  CREATE VIEW view uscustomers AS SELECT customerid  customername FROM customers WHERE countryid  US     This command creates a new view called view uscustomers  Note that this command does not result in anything being actually stored in the database at all except for a data dictionary entry that defines this view  This means that every time you query this view  Oracle has to go out and execute the view and query the database data  We can query the view like this   SELECT   FROM view uscustomers WHERE customerid BETWEEN 100 AND 200    And Oracle will transform the query into this   SELECT    FROM  select customerid  customername from customers WHERE countryid  US    WHERE customerid BETWEEN 100 AND 200   Benefits of using Views   Commonality of code being used  Since a view is based on one common set of SQL  this means that when it is called it   s less likely to require parsing   Security  Views have long been used to hide the tables that actually contain the data you are querying  Also  views can be used to restrict the columns that a given user has access to  Predicate pushing   You can find advanced topics in this article about  How to Create and Manage Views in Oracle

User · Answer

If you like the idea of Views  but are worried about performance you can get Oracle to create a cached table representing the view which oracle keeps up to date  See materialized views

User · Answer

regular view----- short name for a query no additional space is used here  Materialised view---- similar to creating table whose data will refresh periodically based on data query used for creating the view

User · Answer

A View in Oracle and in other database systems is simply the representation of a SQL statement that is stored in memory so that it can easily be re-used  For example  if we frequently issue the following query  SELECT customerid  customername FROM customers WHERE countryid  US     To create a view use the CREATE VIEW command as seen in this example  CREATE VIEW view uscustomers AS SELECT customerid  customername FROM customers WHERE countryid  US     This command creates a new view called view uscustomers  Note that this command does not result in anything being actually stored in the database at all except for a data dictionary entry that defines this view  This means that every time you query this view  Oracle has to go out and execute the view and query the database data  We can query the view like this   SELECT   FROM view uscustomers WHERE customerid BETWEEN 100 AND 200    And Oracle will transform the query into this   SELECT    FROM  select customerid  customername from customers WHERE countryid  US    WHERE customerid BETWEEN 100 AND 200   Benefits of using Views   Commonality of code being used  Since a view is based on one common set of SQL  this means that when it is called it   s less likely to require parsing   Security  Views have long been used to hide the tables that actually contain the data you are querying  Also  views can be used to restrict the columns that a given user has access to  Predicate pushing   You can find advanced topics in this article about  How to Create and Manage Views in Oracle

User · Answer

If you like the idea of Views  but are worried about performance you can get Oracle to create a cached table representing the view which oracle keeps up to date  See materialized views

User · Answer

A View in Oracle and in other database systems is simply the representation of a SQL statement that is stored in memory so that it can easily be re-used  For example  if we frequently issue the following query  SELECT customerid  customername FROM customers WHERE countryid  US     To create a view use the CREATE VIEW command as seen in this example  CREATE VIEW view uscustomers AS SELECT customerid  customername FROM customers WHERE countryid  US     This command creates a new view called view uscustomers  Note that this command does not result in anything being actually stored in the database at all except for a data dictionary entry that defines this view  This means that every time you query this view  Oracle has to go out and execute the view and query the database data  We can query the view like this   SELECT   FROM view uscustomers WHERE customerid BETWEEN 100 AND 200    And Oracle will transform the query into this   SELECT    FROM  select customerid  customername from customers WHERE countryid  US    WHERE customerid BETWEEN 100 AND 200   Benefits of using Views   Commonality of code being used  Since a view is based on one common set of SQL  this means that when it is called it   s less likely to require parsing   Security  Views have long been used to hide the tables that actually contain the data you are querying  Also  views can be used to restrict the columns that a given user has access to  Predicate pushing   You can find advanced topics in this article about  How to Create and Manage Views in Oracle

[database] What is a View in Oracle?

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