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30 gru 2023 · The cascading referential integrity constraints in SQL servers are the foreign key constraints that tell SQL servers to perform certain actions whenever a user attempts to delete or update a primary key to which an existing foreign key points. What is Cascade?
Cascade Update. Cascade Update may make sense when you use a real key rather than a surrogate key (identity/autoincrement column) across tables. The canonical example for Cascade Update is when you have a mutable foreign key, like a username that can be changed.
20 cze 2013 · SQL:2011 Spec. There are five options for ON DELETE and ON UPDATE that can apply to the FOREIGN KEY. These are called <referential actions>, directly from the SQL:2011 spec. ON DELETE CASCADE: if a row of the referenced table is deleted, then all matching rows in the referencing table are deleted.
SQL Server T-SQL clauses such are “ON Delete Cascade” and “ON Update Cascade” are not new in SQL Server, but cascading on a temporal table was not allowed in SQL Server 2016. We will walk through the example in SQL Server 2017 to see how these 2 clauses work and how data is effected in the child table when the parent table is modified.
1 sie 2012 · Here's an example from codeproject with a good explanation of the use of the delete cascade topic "Use the ON DELETE CASCADE option if you want rows deleted in the child table when corresponding rows are deleted in the parent table.
12 lip 2013 · Use the ON DELETE CASCADE option if you want rows deleted in the child table when corresponding rows are deleted in the parent table. If you do not specify cascading deletes, the default behavior of the database server prevents you from deleting data in a table if other tables reference it.
1 lip 2020 · Cascading referential integrity constraints are foreign key constraints that is used to defines the action that SQL Server performs when a user try to delete or update a primary key value to which an existing foreign key points.
