Trigger updating column

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At this time SQLite supports only FOR EACH ROW triggers, not FOR EACH STATEMENT triggers.Hence explicitly specifying FOR EACH ROW is optional.Assuming that customer records are stored in the "customers" table, and that order records are stored in the "orders" table, the following UPDATE trigger ensures that all associated orders are redirected when a customer changes his or her address: CREATE TABLE customer( cust_id INTEGER PRIMARY KEY, cust_name TEXT, cust_addr TEXT ); CREATE VIEW customer_address AS SELECT cust_id, cust_addr FROM customer; CREATE TRIGGER cust_addr_chng INSTEAD OF UPDATE OF cust_addr ON customer_address BEGIN UPDATE customer SET cust_addr=NEW.cust_addr WHERE cust_id=NEW.cust_id; END; Causes the customer.cust_addr field to be updated for a specific customer entry that has customer.cust_id equal to the $cust_id parameter.Note how the values assigned to the view are made available as field in the special "NEW" table within the trigger body.

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A trigger may be specified to fire whenever a DELETE, INSERT, or UPDATE of a particular database table occurs, or whenever an UPDATE occurs on on one or more specified columns of a table.FOR EACH ROW implies that the SQL statements specified in the trigger may be executed (depending on the WHEN clause) for each database row being inserted, updated or deleted by the statement causing the trigger to fire.Both the WHEN clause and the trigger actions may access elements of the row being inserted, deleted or updated using references of the form "NEW.column-name" and "OLD.column-name", where column-name is the name of a column from the table that the trigger is associated with.A special SQL function RAISE() may be used within a trigger-program, with the following syntax raise-function: When one of RAISE(ROLLBACK,...), RAISE(ABORT,...) or RAISE(FAIL,...) is called during trigger-program execution, the specified ON CONFLICT processing is performed the current query terminates.An error code of SQLITE_CONSTRAINT is returned to the application, along with the specified error message.

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