Add SQL Dates entry for 'ADDDATE()'

content/sql/concepts/dates/terms/adddate/adddate.md

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+---
+Title: 'ADDDATE()'
+Description: 'Adds a specific interval to a given date.'
+Subjects:
+  - 'Computer Science'
+  - 'Data Science'
+Tags:
+  - 'Database'
+  - 'Date'
+  - 'Queries'
+  - 'SQL Server'
+CatalogContent:
+  - 'learn-sql'
+  - 'paths/analyze-data-with-sql'
+---
+
+**`ADDDATE()`** in SQL returns a new date by adding a specified time interval (such as days, months, or years) to a given date.
+
+## Syntax
+
+There are two versions of this operator.
+
+```pseudo
+SELECT ADDDATE(date, days);
+```
+
+...or...
+
+```pseudo
+SELECT ADDDATE(date, INTERVAL value unit);
+```
+
+**Parameters:**
+
+- `date` (required): the date or datetime value (see [SQL Date Formats](https://www.codecademy.com/resources/docs/sql/date-format) for more information)
+- `days` (required): the number of days to add to `date`
+- `unit` (required): the unit of date/time to add
+  - The specified unit is one of the following:
+    - `MICROSECOND`
+    - `SECOND`
+    - `MINUTE`
+    - `HOUR`
+    - `DAY`
+    - `WEEK`
+    - `MONTH`
+    - `QUARTER`
+    - `YEAR`
+    - `SECOND_MICROSECOND`
+    - `MINUTE_MICROSECOND`
+    - `MINUTE_SECOND`
+    - `HOUR_MICROSECOND`
+    - `HOUR_SECOND`
+    - `HOUR_MINUTE`
+    - `DAY_MICROSECOND`
+    - `DAY_SECOND`
+    - `DAY_MINUTE`
+    - `DAY_HOUR`
+    - `YEAR_MONTH`
+- `value` (required): the value of the given date/time interval (`unit`) to add
+
+> Note: `ADDDATE` is specific to MySQL. A similar function exists in SQL Server under the function [`DATEADD`](https://www.codecademy.com/resources/docs/sql/dates/dateadd) which has its own set of parameters.
+
+## Example 1
+
+Let's add a few days to the date `2026-01-16`. This can be achieved using both `ADDDATE()` variations.
+
+```sql
+-- Using days = 5
+SELECT ADDDATE('2026-01-16', 5);
+
+-- Using value = 5 and unit = DAY
+SELECT ADDDATE('2026-01-16', INTERVAL 5 DAY);
+```
+
+Both queries will return the following output:
+
+```shell
+2026-01-21
+```
+
+In the same vein, `ADDDATE(date, 7)` and `ADDDATE(date, INTERVAL 1 WEEK)` will return the same result, as well as both `ADDDATE(datetime, INTERVAL 60 SECOND)` and `ADDDATE(datetime, INTERVAL 1 MINUTE)`.
+
+## Example 2
+
+The parameter `unit` can be one of the following composite interval expressions and their respective formats.
+
+| expression           | format                               |
+| -------------------- | ------------------------------------ |
+| `SECOND_MICROSECOND` | `SECOND.MICROSECOND`                 |
+| `MINUTE_MICROSECOND` | `MINUTE:SECOND.MICROSECOND`          |
+| `MINUTE_SECOND`      | `MINUTE:SECOND`                      |
+| `HOUR_MICROSECOND`   | `HOUR:MINUTE:SECOND.MICROSECOND`     |
+| `HOUR_SECOND`        | `HOUR:MINUTE:SECOND`                 |
+| `HOUR_MINUTE`        | `HOUR:MINUTE`                        |
+| `DAY_MICROSECOND`    | `DAY HOUR:MINUTE:SECOND.MICROSECOND` |
+| `DAY_SECOND`         | `DAY HOUR:MINUTE:SECOND`             |
+| `DAY_MINUTE`         | `DAY HOUR:MINUTE`                    |
+| `DAY_HOUR`           | `DAY HOUR`                           |
+| `YEAR_MONTH`         | `YEAR-MONTH`                         |
+
+`DAY_HOUR` example:
+
+```sql
+-- '7 1' is 7 days and 1 hour
+SELECT ADDDATE('2026-09-25 14:00:00', INTERVAL '7 1' DAY_HOUR);
+```
+
+```shell
+2026-10-02 15:00:00
+```
+
+`YEAR_MONTH` example:
+
+```sql
+-- '1-1' is 1 year and 1 month
+SELECT ADDDATE('2026-09-25', INTERVAL '1-1' YEAR_MONTH)
+```
+
+```shell
+2027-10-25
+```
+
+`HOUR_SECOND` example:
+
+```sql
+-- '6:23:42' is 6 hours, 23 minutes and 42 seconds
+SELECT ADDDATE('2026-09-25 14:00:00', INTERVAL '6:23:42' HOUR_SECOND);
+```
+
+```shell
+2026-09-25 20:23:42
+```
+
+`SECOND_MICROSECOND` example:
+
+```sql
+-- '2.837' is 2 seconds and 837 microseconds
+SELECT ADDDATE('2026-09-25 16:00:00', INTERVAL '2.837' SECOND_MICROSECOND);
+```
+
+```shell
+2026-09-25 16:00:02.837000
+```
+
+## Example 3
+
+Consider the following list of San Diego bus routes and their arrival times. This table will be named `sd_bus_routes`.
+
+```sql
+-- Create table
+CREATE TABLE sd_bus_routes (
+  ROUTE_ID INT PRIMARY KEY,
+  ROUTE_NAME VARCHAR(100),
+  ARRIVAL_TIME DATETIME
+);
+
+-- Insert bus routes
+INSERT INTO sd_bus_routes (ROUTE_ID, ROUTE_NAME, ARRIVAL_TIME)
+VALUES
+  (1, 'Fashion Valley - La Mesa', '2026-08-28 16:11:00'),
+  (2, 'Downtown - North Park', '2026-08-28 16:14:00'),
+  (3, 'UCSD Med. Ctr. / Hillcrest Euclid Trolley', '2026-08-28 16:26:00');
+```
+
+```shell
+| ROUTE_ID | ROUTE_NAME                                | ARRIVAL_TIME        |
+| -------- | ----------------------------------------- | ------------------- |
+| 1        | Fashion Valley - La Mesa                  | 2026-08-28 16:11:00 |
+| 2        | Downtown - North Park                     | 2026-08-28 16:14:00 |
+| 3        | UCSD Med. Ctr. / Hillcrest Euclid Trolley | 2026-08-28 16:26:00 |
+```
+
+August 28, 2026 is a Friday and the timestamps are in the afternoon, so the conditions are right for expected delays. Let's add a new column to this table to reflect this.
+
+```sql
+-- Add new column
+ALTER TABLE sd_bus_routes
+ADD UPDATED_ARRIVAL_TIME DATETIME;
+```
+
+```shell
+| ROUTE_ID | ROUTE_NAME                                | ARRIVAL_TIME        | UPDATED_ARRIVAL_TIME |
+| -------- | ----------------------------------------- | ------------------- | -------------------- |
+| 1        | Fashion Valley - La Mesa                  | 2026-08-28 16:11:00 | null                 |
+| 2        | Downtown - North Park                     | 2026-08-28 16:14:00 | null                 |
+| 3        | UCSD Med. Ctr. / Hillcrest Euclid Trolley | 2026-08-28 16:26:00 | null                 |
+```
+
+Let's say all three routes will be delayed due to San Diego traffic: route 1 by 10 minutes, route 2 by 12 minutes, and route 3 by 15 minutes. Let's update values in the new column by runing `ADDDATE` for each respective `ARRIVAL_TIME` value.
+
+```sql
+-- Set new arrival times
+UPDATE sd_bus_routes
+SET UPDATED_ARRIVAL_TIME =
+(
+  CASE
+    WHEN ROUTE_ID = 1
+      THEN ADDDATE(ARRIVAL_TIME, INTERVAL 10 MINUTE)
+    WHEN ROUTE_ID = 2
+      THEN ADDDATE(ARRIVAL_TIME, INTERVAL 12 MINUTE)
+    WHEN ROUTE_ID = 3
+      THEN ADDDATE(ARRIVAL_TIME, INTERVAL 15 MINUTE)
+  END
+);
+```
+
+The table now has the updated arrival times.
+
+```shell
+| ROUTE_ID | ROUTE_NAME                                | ARRIVAL_TIME        | UPDATED_ARRIVAL_TIME |
+| -------- | ----------------------------------------- | ------------------- | -------------------- |
+| 1        | Fashion Valley - La Mesa                  | 2026-08-28 16:11:00 | 2026-08-28 16:21:00  |
+| 2        | Downtown - North Park                     | 2026-08-28 16:14:00 | 2026-08-28 16:26:00  |
+| 3        | UCSD Med. Ctr. / Hillcrest Euclid Trolley | 2026-08-28 16:26:00 | 2026-08-28 16:41:00  |
+```