Performing an implicit data type conversion requires that an appropriate cast definition exists that specifies the AS ASSIGNMENT clause.
Teradata Database performs implicit UDT-to-DATE conversions for the following operations:
- UPDATE
- INSERT
- Passing arguments to stored procedures, external stored procedures, UDFs, and UDMs
- Specific system operators and functions identified in other sections of this document, unless the DisableUDTImplCastForSysFuncOp field of the DBS Control Record is set to TRUE
If no UDT-to-DATE implicit cast definition exists, Teradata Database looks for other cast definitions that can substitute for the UDT-to-DATE implicit cast definition:
| Combination of Implicit Cast Definitions | Description | |
|---|---|---|
| UDT-to-Numeric | UDT-to-Character (non-CLOB) |
|
| X | Teradata Database uses the UDT-to-numeric implicit cast definition. If multiple UDT-to-numeric implicit cast definitions exist, then Teradata Database returns an SQL error. |
|
| X | Teradata Database uses the UDT-to-character implicit cast definition. If multiple UDT-to-character implicit cast definitions exist, then Teradata Database returns an SQL error. |
|
| X | X | Teradata Database reports an error. |
Substitutions are valid because Teradata Database can use the implicit cast definition to cast the UDT to the substitute data type, and then implicitly cast the substitute data type to a DATE type.