The FROM clause of queries involving temporal tables can now accept CURRENT and NONSEQUENCED for VALIDTIME and TRANSACTIONTIME qualifiers, in addition to an AS OF qualifier. The AS OF qualifier can now accept a column expression.
- Additional flexibility for queries on temporal tables.
- Allows mixing of temporal qualifiers at the statement and individual table levels of a query.
- A temporal qualifier in a FROM clause takes precedence over a qualifier for the same temporal dimension at the statement level.
- The valid-time or transaction-time column of a temporal table referenced in the FROM clause is considered to be in the scope of the query, and can therefore be referenced anywhere in the query, such as in a WHERE or JOIN condition.
- If date_timestamp_expression of an AS OF qualifier references a table column, Teradata Database applies the AS OF qualifier to the temporal table for each value in the referenced column, and returns the combination of all results.
- The table associated with a temporal qualifier in the FROM clause of an UPDATE or DELETE statement cannot be the table that the DELETE or UPDATE statement modifies.
FROM clause (temporal form)
For more information about the FROM clause (temporal form), see Teradata Vantage™ Temporal Table Support , B035-1182 .