|SQL Language Reference / Statements|
Update the value of one or more columns.
This form of the UPDATE statement is called a searched update. It updates the value of one or more columns for all rows of the table for which the WHERE clause evaluates to TRUE. Specifying DEFAULT for the update value sets the value of the column to the default defined for that table.
The UPDATE statement returns the number of rows that were updated.
expression | DEFAULT
A searched update statement depends on the table being updated, all of its conglomerates (units of storage such as heaps or indexes), all of its constraints, and any other table named in the WHERE clause or SET expressions.
A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared searched update statement invalidates the prepared searched update statement.
A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared positioned update invalidates the prepared positioned update statement.
Dropping a synonym invalidates a prepared update statement if the latter statement uses the synonym.
Dropping or adding triggers on the target table of the update invalidates the update statement.
-- Change the ADDRESS and SINCE fields to null for all customers with ID greater than 10. UPDATE TRADE.CUSTOMERS SET ADDR=NULL, SINCE=NULL WHERE CID > 10; -- Set the ADDR of all customers to 'VMWare' where the current address is NULL. UPDATE TRADE.CUSTOMERS SET ADDR = 'VMWare' WHERE ADDR IS NULL; // Increase the QTY field by 10 for all rows of SELLORDERS table. UPDATE TRADE.SELLORDERS SET QTY = QTY+10; -- Change the STATUS field of all orders of SELLORDERS table to DEFAULT ( 'open') , for customer ID = 10 UPDATE TRADE.SELLORDERS SET STATUS = DEFAULT WHERE CID = 10;