{"id":1254,"date":"2025-04-06T16:29:13","date_gmt":"2025-04-06T16:29:13","guid":{"rendered":"https:\/\/learnlearn.uk\/ibcs\/?page_id=1254"},"modified":"2025-04-06T16:31:04","modified_gmt":"2025-04-06T16:31:04","slug":"database-views","status":"publish","type":"page","link":"https:\/\/learnlearn.uk\/ibcs\/database-views\/","title":{"rendered":"Database Views"},"content":{"rendered":"
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Introduction<\/h2>\n
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What are Database Views?<\/h2>\n

Database views are\u00a0virtual tables<\/b>\u00a0that provide a specific representation of data from one or more tables in a database. Unlike physical tables, views do not store data themselves; instead, they\u00a0display data stored in other tables<\/b>. This allows for a simplified and focused access to complex datasets.<\/p>\n

They simplify complex queries, presenting users with a more manageable data structure, and can enhance data security by\u00a0restricting access to specific columns or rows<\/b>.<\/p>\n\n<\/div>

Creating Views<\/h2>\n
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Creating a Database View in SQL<\/h2>\n

Creating a database view in SQL involves defining a virtual table based on the result set of a SELECT query. This allows users to simplify complex queries and enhance data accessibility. Views can represent a subset of data or aggregate information from multiple tables.<\/p>\n

To create a view, the SQL statement ‘CREATE VIEW’ is used followed by the view name and the SELECT statement defining the view’s contents. Understanding how to effectively create and manage views can significantly streamline database interactions.<\/p>\n\n<\/div>

Advantages<\/h2>\n
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Advantages of Database Views<\/h2>\n

Improving Data Security<\/h3>\n

In sensitive environments, views restrict user access to certain data without exposing the complete database. This allows organizations to comply with privacy regulations while allowing users to perform necessary functions.<\/p>\n

Simplifying Complex Queries<\/h3>\n

By encapsulating complex joins and calculations, views make it easier for users to interact with data. This is particularly useful in reporting and analytics, where users can retrieve necessary insights without deep database knowledge.<\/p>\n\n<\/div>

Drawbacks<\/h2>\n
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Drawbacks of Database Views<\/h2>\n

Database views can introduce additional overhead, especially if they involve complex queries or join operations. This can lead to slower response times if not managed properly.<\/p>\n\n<\/div>

Example<\/h2>\n
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Example Database View<\/h2>\n

Suppose we have two tables: employees and departments.<\/p>\n

Employees Table<\/h2>\n\n\n\n\n\n\n\n\n
employee_id<\/th>\nfirst_name<\/th>\nlast_name<\/th>\ndepartment_id<\/th>\nsalary<\/th>\n<\/tr>\n<\/thead>\n
1<\/td>\nJohn<\/td>\nDoe<\/td>\n101<\/td>\n50000<\/td>\n<\/tr>\n
2<\/td>\nJane<\/td>\nSmith<\/td>\n102<\/td>\n60000<\/td>\n<\/tr>\n
3<\/td>\nJim<\/td>\nBrown<\/td>\n101<\/td>\n45000<\/td>\n<\/tr>\n
4<\/td>\nEmily<\/td>\nDavis<\/td>\n103<\/td>\n70000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Departments Table<\/h2>\n\n\n\n\n\n\n\n
department_id<\/th>\ndepartment_name<\/th>\n<\/tr>\n<\/thead>\n
101<\/td>\nHR<\/td>\n<\/tr>\n
102<\/td>\nIT<\/td>\n<\/tr>\n
103<\/td>\nFinance<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n<\/div>

SQL<\/h2>\n
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SQL to create the view<\/h2>\n

We want to create a view that shows the employee’s full name and the department they work in, with the salary information.<\/p>\n

SQL to create the view:<\/p>\n

\n
CREATE<\/span> VIEW<\/span> employee_department_view AS<\/span>
\nSELECT<\/span> e.first_name ||<\/span> ' '<\/span> ||<\/span> e.last_name AS<\/span> full_name,
\ne.salary,
\nd.department_name
\nFROM<\/span> employees e
\nJOIN<\/span> departments d ON<\/span> e.department_id =<\/span> d.department_id;<\/code><\/div>\n<\/div>\n\n<\/div>

Resuls<\/h2>\n
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Result of the View<\/h2>\n

The view will provide a combined result from the\u00a0employees<\/strong>\u00a0and\u00a0departments<\/strong>\u00a0tables.<\/h3>\n\n\n\n\n\n\n\n\n
full_name<\/th>\nsalary<\/th>\ndepartment_name<\/th>\n<\/tr>\n<\/thead>\n
John Doe<\/td>\n50000<\/td>\nHR<\/td>\n<\/tr>\n
Jane Smith<\/td>\n60000<\/td>\nIT<\/td>\n<\/tr>\n
Jim Brown<\/td>\n45000<\/td>\nHR<\/td>\n<\/tr>\n
Emily Davis<\/td>\n70000<\/td>\nFinance<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

How it works:<\/h3>\n

 <\/p>\n