### BIT_OR Function
```sql
bit_or([distinct] expr)
```
#### Function Description
The BIT_OR function is used to compute the bitwise OR result of a set of integer expressions. This function can handle integer types including tinyint, smallint, int, and bigint. By using this function, you can manipulate the binary bits of the input data to achieve specific data processing needs.

#### Parameter Description
* expr: The integer expression to be bitwise OR-ed, with types tinyint, smallint, int, or bigint.
* distinct (optional): When set to distinct, the function will compute the bitwise OR result of the distinct set of expressions. If distinct is not set, the function will compute the result for all expressions, including duplicates.

#### Return Results
* The return type is consistent with the parameter type.
* If all input values are null, it returns null.
* If no non-null expressions are provided, it returns 0.

#### Usage Example
1. Compute the bitwise OR result of a set of values:
```sql
SELECT bit_or(col) FROM VALUES (3), (5), (7) AS tab(col);
-- Result: 7
```
2. Calculate the bitwise OR result of the deduplicated value set:
```sql
SELECT bit_or(DISTINCT col) FROM VALUES (3), (3), (5), (7), (null) AS tab(col);
-- Result: 7
```
3. Calculate the bitwise OR result of a set of numbers containing null values:
```sql
SELECT bit_or(col) FROM VALUES (null), (3), (5) AS tab(col);
-- Result: 5
```
4. For a situation where a set consists entirely of null values:
```sql
SELECT bit_or(col) FROM VALUES (null), (null) AS tab(col);
-- Result: null
```
#### Precautions
* The BIT_OR function operates on the binary bits of the input data, so it is necessary to understand the principles and effects of bitwise OR operations when using it.
* When the expression being processed contains null values, be aware that the return result may be null.
* If you need to calculate the bitwise OR result after deduplication, please use the distinct keyword.