Date and time expressions

A datetime expression is used to generate values of the datetime data type or perform operations on datetime values.

Syntax of date and time expressions

date_expr { + | - } INTERVAL expr date_unit

Common values of date_unit include:

• DAY、WEEK、MONTH、QUARTER、YEAR
• HOUR、MINUTE、SECOND、MICROSECOND
• Compound units: DAY_HOUR, DAY_MINUTE, DAY_second, HOUR_MINUTE, HOUR_SECOND, YEAR_MONTH, and so on.

For the complete list of date_unit, see the date_unit production rule in Expression syntax.

Usage instructions

• date_expr can be a column or expression of the DATE, DATETIME, or TIMESTAMP type.
• INTERVAL expr date_unit specifies a time interval.
• When date_expr is added to or subtracted from INTERVAL, the result is a new datetime value.

Examples

Add 7 days to the current date:

obclient> SELECT NOW() + INTERVAL 7 DAY;
+----------------------------+
| NOW() + INTERVAL 7 DAY     |
+----------------------------+
| 2026-06-09 17:13:00        |
+----------------------------+
1 row in set

Subtract 1 month from the current date:

obclient> SELECT NOW() - INTERVAL 1 MONTH;
+----------------------------+
| NOW() - INTERVAL 1 MONTH   |
+----------------------------+
| 2026-05-02 17:13:00        |
+----------------------------+
1 row in set