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The syntax for creating a foreign key with cascade delete in an ALTER TABLE statement in Oracle/PLSQL is: ALTER TABLE table_name ADD CONSTRAINT constraint_name FOREIGN KEY (column1, column2, ... column_n) REFERENCES parent_table (column1, column2, ... column_n) ON DELETE CASCADE;
20 gru 2011 · If you design your database using primary / foreign keys it will be easier to delete using cascading-deletes than searching manually where do you have foreign keys on which column and table and generate matching SQL statements.
This tutorial shows how to use Oracle DELETE FROM statement to delete one or more rows from a table. It also explains how to delete cascade works.
11 wrz 2024 · The ON DELETE CASCADE clause is used in PL/SQL to automatically delete related records in a child table when the corresponding record in the parent table is deleted. This ensures referential integrity by preventing orphaned records in the child table.
Oracle 12c introduced the CASCADE clause of the TRUNCATE TABLE command, allowing you to recursively truncate down the tables in a hierarchy. The functionality requires all referential integrity constraints involved to be defined using the ON DELETE CASCADE clause.
20 cze 2013 · ON DELETE CASCADE: if a row of the referenced table is deleted, then all matching rows in the referencing table are deleted. ON DELETE SET NULL : if a row of the referenced table is deleted, then all referencing columns in all matching rows of the referencing table to be set to null.
14 maj 2004 · I want to write cascade delete trigger on a table. What I want is to SET NULL in child records for every parent records I want to delete. I have written BEFORE ROW LEVEL trigger to trap the parent key value and BEFORE STATEMENT LEVEL to update the child record to null for that parent key.
