The following table shows the result of the CAST function or Teradata conversion based on the various options specified. Note that the time zone adjustment may change the YEAR, MONTH, and DAY fields of the DATE value.
| IF you specify... | AND the data type of timestamp_expression is... | THEN... |
|---|---|---|
| AT LOCAL | with or without TIME ZONE | the result is the date portion of the source timestamp_expression after adjusting its UTC value by adding the time zone displacement based on the current session time zone. This is the same as not specifying the AT clause. |
| AT SOURCE (where SOURCE is a keyword and not a column reference) |
WITH TIME ZONE | the result is the date portion of the source timestamp_expression after adjusting its UTC value by adding the time zone displacement associated with timestamp_expression. |
| AT SOURCE (where SOURCE is a keyword and not a column reference) |
without TIME ZONE | an error is returned. |
| AT SOURCE TIME ZONE | WITH TIME ZONE | the result is the date portion of the source timestamp_expression after adjusting its UTC value by adding the time zone displacement associated with timestamp_expression. |
| AT SOURCE TIME ZONE | without TIME ZONE | an error is returned. |
| AT expression or AT TIME ZONE expression |
with or without TIME ZONE | the result is the date portion of the source timestamp_expression after adjusting its UTC value by adding the time zone displacement defined by expression. |
| AT time_zone_string or AT TIME ZONE time_zone_string |
with or without TIME ZONE | the result is the date portion of the source timestamp_expression after adjusting its UTC value by adding the time zone displacement based on time_zone_string. The time zone displacement is determined based on time_zone_string and the TIMESTAMP value of timestamp_expression |