### ADD\_YEARS 
```
add_years(startDate, numYears)
```
####  Description

This function is used to calculate and return the date after adding (or subtracting) a specified number of years (numYears) to a given start date (startDate). If the calculated result exceeds the date range supported by the system, it will return null.

#### Parameter Description

* startDate: Type date, represents the start date for the calculation.
* numYears: Type int, represents the number of years to add or subtract, can be positive or negative.

#### Return Result

Returns a date type date, representing the calculated result.

#### Usage Example

1. Calculate a future date:
```sql
SELECT add_years('2020-05-31', 3);
+----------------------------+
| add_years('2020-05-31', 3) |
+----------------------------+
| 2023-05-31                 |
+----------------------------+
```
2. Calculate past dates:
```sql
SELECT add_years('2020-05-31', -5);
+-----------------------------+
| add_years('2020-05-31', -5) |
+-----------------------------+
| 2015-05-31                  |
+-----------------------------+
```
3. When the added years cause the result to exceed the system date range, return null:
```sql
SELECT add_years('1900-01-01', 200);
+------------------------------+
| add_years('1900-01-01', 200) |
+------------------------------+
| 2100-01-01                   |
+------------------------------+1
```
#### Precautions

* Ensure that the input startDate parameter is in a valid date format, otherwise it may lead to inaccurate calculation results.
* When numYears is a negative number, it indicates calculating the corresponding number of years backward from the start date.
* If the calculation result exceeds the date range supported by the system, the function will return null. Please handle this situation accordingly.

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