The Teradata implementation of ANSI/ISO Temporal tables and syntax is extended to include the following non-ANSI standard capabilities:
- The ANSI/ISO standard allows for a maximum of only two derived period columns in a temporal table, one for valid time and one for system time. ANSI temporal tables in Teradata Database can have more than two derived period columns.
- The ANSI/ISO standard does not define a CONTAINED IN qualifier for querying system-time tables. The CONTAINED IN qualifier can be used to query ANSI system-time tables in the database. See Querying ANSI System-Time Tables.
- The ANSI/ISO standard does not define special temporal qualifiers for querying valid-time tables. ANSI temporal valid-time tables in the database can be queried using the same temporal qualifiers as can be used for querying ANSI system-versioned system-time tables (AS OF, BETWEEN..AND, FROM...TO, and CONTAINED IN).
- The ANSI/ISO standard for creating valid-time tables does not require or support the [AS] VALIDTIME column attribute. ANSI temporal valid-time tables in Teradata Database require [AS] VALIDTIME as part of the column specification in the table definition.
- The ANSI/ISO standard does not support the temporal qualifiers and constraints that are used in the Teradata proprietary implementation of temporal tables that was developed prior to the release of the ANSI/ISO standard for temporal tables. Temporal qualifiers and constraints used on Teradata proprietary temporal tables can be used with the Teradata implementation of ANSI temporal tables. For more information about these constraints and qualifiers, see Teradata Vantage™ - Temporal Table Support , B035-1182 .