Modifies column values in existing rows of system-time tables.
Syntax
There is no special additional temporal syntax for the UPDATE statement when used on a system-time table. The syntax is identical to that used for nontemporal tables. That syntax is described fully in Teradata Vantage™ - SQL Data Manipulation Language, B035-1146.
Usage Notes
Although the syntax for a UPDATE statement is identical for system-time and non-temporal tables, the effects are different. When you change a row in a nontemporal table, the original information in the row no longer exists. The situation can be thought of as if the original row had been deleted and replaced with a new row.
System-time tables make this implicit situation explicit, by literally deleting the original row from the table and inserting a new row into the table to reflect the modified information. Because rows are never physically deleted from system-time tables, the original row is closed in system time, and remains inactive in the table as a snapshot of how the table existed before the change.
Updates so not affect closed rows in system-time tables.
The SET clause cannot include the beginning or ending column components of the SYSTEM_TIME derived period column.