If a date-time value is the operand of addition, the other operand must be a duration. The rules for subtracting are different because a date-time value cannot be subtracted from a duration, and subtracting two date-time values differs from subtracting a duration from a date-time value. The rules for date-time arithmetic are shown in the following table.
Addition Rules
| If one operand is a...
|
...the other operand must be a...
|
| Date
|
- Date Duration
- Labeled Duration of years, months or days
|
| Time
|
- Time Duration
- Labeled Duration of hours, minutes or seconds
|
| Timestamp
|
- Timestamp Duration
- Labeled Duration of years, months, days, hours, minutes or seconds
|
Subtraction Rules
| If the FIRST operand is a...
|
...the SECOND operand must be a...
|
| Date
|
- Date
- Date Duration
- String representation of a date
- Labeled duration of years, months or days
|
| Time
|
- Time
- Time Duration
- String representation of a time
- Labeled duration of hours, minutes or seconds
|
| Timestamp
|
- Timestamp
- Timestamp Duration
- Date Duration
- Time Duration
- String representation of a timestamp
- Labeled duration of years, months, days, hours, minutes or seconds
|
| If the SECOND operand is a...
|
...the FIRST operand must be a...
|
| Date
|
- Date
- String representation of a date
|
| Time
|
- Time
- String representation of a time
|
| Timestamp
|
- Timestamp
- String representation of a timestamp
|
More:
-
Subtracting Dates
-
Incrementing and Decrementing Dates
-
Subtracting Times
-
Incrementing and Decrementing Times
-
Subtracting Timestamps
-
Incrementing and Decrementing Timestamps
-
Examples: Date/Time Arithmetic
