TIMESTAMP special value

The TIMESTAMP default value is used to record the local date and time of day when a row in a table was last modified.

Remarks

The fraction of a second is stored to 6 decimal places. The accuracy of the present time is limited by the accuracy of the system clock.

When a column is declared with DEFAULT TIMESTAMP, a default value is provided for inserts, and the value is updated with the present date and time of day whenever the row is updated.

Columns declared with DEFAULT TIMESTAMP contain unique values so that applications can detect near-simultaneous updates to the same row. If the present timestamp value is the same as the last value, it is incremented by the value of the default_timestamp_increment option.

You can automatically truncate timestamp values in SQL Anywhere based on the default_timestamp_increment option. This is useful for maintaining compatibility with other database software that records less precise timestamp values.

The global variable @@dbts returns a TIMESTAMP value representing the last value generated for a column using DEFAULT TIMESTAMP.

Note

The main difference between DEFAULT TIMESTAMP and DEFAULT CURRENT TIMESTAMP is that DEFAULT CURRENT TIMESTAMP is set only at INSERT, while DEFAULT TIMESTAMP is set at both INSERT and UPDATE.

Standards and compatibility

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