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What is the difference between a view and a query?
Views are a special version of tables in SQL. The view is a query stored in the data dictionary, on which the user can query just like they do on tables. It does not use the physical memory, only the query is stored in the data dictionary. It is computed dynamically, whenever the user performs any query on it.
Is it faster to query a view?
Views make queries faster to write, but they don’t improve the underlying query performance. In short, if an indexed view can satisfy a query, then under certain circumstances, this can drastically reduce the amount of work that SQL Server needs to do to return the required data, and so improve query performance.
Why use a view instead of a query?
Views can provide many advantages over tables: Views can represent a subset of the data contained in a table. Views can limit the degree of exposure of the underlying tables to the outer world: a given user may have permission to query the view, while denied access to the rest of the base table.
Is there any significant difference between fetch and query?
Is there any significant difference between them? The Database class has two methods for retrieving records Query and Fetch. These are pretty much identical except Fetch returns a List<> of POCO’s whereas Query uses yield return to iterate over the results without loading the whole set into memory.
When to use select or select from view?
If you modify your view definition adding new columns, you can break a program using “select *”, whereas selecting a predefined set of columns (even all of them, named), will still work. I guess it all depends on what the query optimizer does. If I want to get every record in the row, I will generally use the “SELECT *…”
How does Microsoft query work with external data?
Microsoft Query uses the data source to connect to the external database and to show you what data is available. After you create your query and return the data to Excel, Microsoft Query provides the Excel workbook with both the query and data source information so that you can reconnect to the database when you want to refresh the data.
How does react query work to fetch data?
In a React Query application, when a page loads the first time, the library will fetch the data from the API, present it to you and then cache it. You’ll notice a “loading” message when this happens. When you visit this page a second time, React Query will first return data from the cache and then perform a fetch in the background.