A view in SQL is a saved query that can be reused like a table, but does not store the data itself. It displays data from one or more tables at runtime, like a window in a database. The main uses of views include: 1. Simplify complex queries - save long and repeated queries as views for subsequent calls; 2. Improve security - restrict users to access specific columns or rows through views; 3. Maintain consistency - ensure that multiple people get the same filtering or calculation results. Create views using CREATE VIEW statements, such as creating views that display high-priced products: CREATE VIEW expensive_products AS SELECT product_name, price FROM products WHERE price > 1000; After creation, you can query like a normal table. Note that the view does not store data, so the latest information will be obtained from the source table every time it is executed. Potential issues should also be noted when using views: 1. Performance impact - Complex queries may slow down execution; 2. Dependencies - Changes in the underlying table structure may cause view errors; 3. Update restrictions - Some databases do not support modifying data through views, especially when it involves connections or aggregations; in addition, naming conflicts should be avoided.

A view in SQL is like a saved query that you can reuse as if it were a table. It doesn't store data itself — instead, it shows data from one or more tables when you run it. Think of it as a window into your database that gives you a specific look at the data without duplicating anything.

Why Use Views?

Views are handy for a few main reasons:

• Simplify complex queries — You can save long, repetitive queries as a view and call them by name later.
• Improve security — You can let users access only certain columns or rows through a view, without giving them full access to the underlying tables.
• Keep things consistent — If multiple people need the same filtered or calculated data, a view ensures everyone gets the same results the same way.

For example, if you often need to see a list of active customers with their total orders, you can create a view for that instead of rewriting the JOIN and WHERE certificates every time.

How to Create a View

Creating a view uses the CREATE VIEW statement. The basic syntax looks like this:

 CREATE VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;

Let's say you want a view showing expensive products:

 CREATE VIEW expensive_products AS
SELECT product_name, price
FROM products
WHERE price > 1000;

Once created, you can query it like a regular table:

 SELECT * FROM expensive_products;

Just remember: since views don't store data, they always pull the latest info from the source tables when you use them.

Things to Watch Out For

Even though views are useful, there are some common gotchas:

• Performance impact — If your view runs a heavy query, it might slow things down every time you use it.
• Dependencies — If the underlying table changes structure, your view might break.
• Not always updatable — Some databases let you update data through a view, but many restrict it, especially if the view uses joins or aggregations.

Also, be careful with naming — make sure your view names don't clash with existing tables or other views.

Basically that's it.

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