1 what is view 2 difference between union and union all. 3.what is indexes 4.difference between primary and unique key. 5.what is composit key.

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Accepted Answer

A view is a virtual table that is based on the result of a query. It is used to simplify complex queries and provide a logical representation of data.

Views are created by selecting columns from one or more tables and can be used like a table in queries.
They do not store any data themselves but provide a way to access and manipulate data from underlying tables.
Views can be used to restrict access to certain columns or rows of a table.
They can also be used to combine data from multiple tables into a single virtual table.

1 what is view 2 difference between union and union all. 3.what is indexes 4.difference between primary and unique key. 5.what is composit key.

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