How to create a view from oracle

Create views in Oracle to provide different perspectives of data without modifying the underlying table. The steps are as follows: 1. Use the CREATE VIEW statement to specify the view name, column name and query; 2. The view column name can be the same as the base table column name, and use AS alias if it is different; 3. The query can contain clauses such as JOIN, WHERE; 4. The creator must have the base table SELECT permission, and other users must obtain the view SELECT permission. View benefits include: data security, simplified access, logical data modeling, and performance improvements.

Create a view in Oracle

A view is a virtual table that derives data from one or more underlying tables. Creating a view allows you to view data in different ways without copying or modifying the original table.

step

1. Create a view statement

Create a view using the CREATE VIEW statement. This statement contains the following:

• View Name: The name you want the view to have.
• Column name: A list of columns to be displayed in the view.
• Query: A query that selects data from the original table.

2. Example

The following example creates a view named customer_view that displays all columns in the table customers and filters the age:

 <code class="sql">CREATE VIEW customer_view AS SELECT * FROM customers WHERE age > 25;</code>

Details

List:

• The column names in the view can be the same or different from the column names of the original table.
• If the column names are different, use the AS keyword in SELECT clause to assign the alias to the column.

Query:

• The query can be the same as any valid SELECT statement of the original table.
• You can use JOIN , WHERE , and other clauses to filter and combine data.

Permissions:

• The user who created the view must have SELECT permissions on the original table.
• Other users can access the view by granting them SELECT permissions to the view.

Advantages

Creating a view has the following advantages:

• Data security: Views can hide sensitive data, such as customer personal information.
• Simplified access: Views can provide a simplified view of complex data, making it easier to query and report.
• Logical data model: Views can represent specific relationships between data, thereby simplifying data modeling.
• Performance: If a view query involves frequently accessed data, it can improve query performance.

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