Video sex chat wid horny girls - Updating the primary key

ON UPDATE CASCADE cannot be specified for tables that have INSTEAD OF UPDATE triggers.

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CASCADE cannot be specified if a timestamp column is part of either the foreign key or the referenced key.

ON DELETE CASCADE cannot be specified for a table that has an INSTEAD OF DELETE trigger.

The Sales Person ID column in the Sales Order Header table matches the primary key column of the Sales Person table.

The Sales Person ID column in the Sales Order Header table is the foreign key to the Sales Person table.

Sales Person table, and the salesperson's ID is used for sales orders in the Sales.

Sales Order Header table, the relational integrity between the two tables is broken; the deleted salesperson's sales orders are orphaned in the Sales Order Header table without a link to the data in the Sales Person table. The constraint enforces referential integrity by guaranteeing that changes cannot be made to data in the primary key table if those changes invalidate the link to data in the foreign key table.Because primary key constraints guarantee unique data, they are frequently defined on an identity column.When you specify a primary key constraint for a table, the Database Engine enforces data uniqueness by automatically creating a unique index for the primary key columns.If the Database Engine encounters NO ACTION, it stops and rolls back related CASCADE, SET NULL and SET DEFAULT actions.When a DELETE statement causes a combination of CASCADE, SET NULL, SET DEFAULT and NO ACTION actions, all the CASCADE, SET NULL and SET DEFAULT actions are applied before the Database Engine checks for any NO ACTION.However, manually creating an index on a foreign key is often useful for the following reasons: Although the main purpose of a foreign key constraint is to control the data that can be stored in the foreign key table, it also controls changes to data in the primary key table.

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