MySQL View Knowledge Point Summary

The view itself is a virtual table and does not hold any data. When accessing a view using an SQL statement, the data it returns is generated by MySQL from other tables. Views and tables are in the same namespace,

MySQL treats views and tables the same way in many places. Views and tables are different, though. For example, you cannot create a trigger on a view or delete a view with the drop TABLE command.

Implementation of the View algorithm:

Merge algorithm: Merge

Temporal table algorithm: tmptable

Updatable views (updatable view): Updates the view to update related tables that are involved in the view.

If the view definition contains group BY, Union, aggregate functions, and some other special cases, it cannot be updated. A query that updates a view can also be an associative statement, but with one restriction, the column being updated must be from the same table. In addition, all views implemented using the Temporal table algorithm cannot be updated.

Check option: Represents any row that is updated through the view and must conform to the Where condition definition of the view itself.

MySQL does not support creating indexes on views.

MySQL does not support building any triggers on the view.

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