### BIT_XOR Function
```sql
bit_xor([distinct] expr)
```
#### Function Description
The BIT_XOR function is used to calculate the bitwise XOR result of a set of integer expressions. Bitwise XOR operation compares the corresponding bits of two binary numbers; if the two bits are the same, the result is 0, and if they are different, the result is 1.

#### Parameter Description
* expr: Integer type expression, supported data types include TINYINT, SMALLINT, INT, BIGINT.
* distinct (optional): If the DISTINCT keyword is specified, the function will calculate the bitwise XOR result of the distinct set of expressions. If DISTINCT is not specified, the function will calculate the bitwise XOR result of all expressions, including duplicates.

#### Return Result
* The return type is consistent with the parameter type.
* If all input values are NULL, it returns NULL.
* If there is at least one non-NULL value, NULL values are not included in the calculation.

#### Usage Example
1. Calculate the bitwise XOR result of a set of values:
```sql
SELECT bit_xor(col) FROM VALUES (3), (5), (7) AS tab(col);
```
Results:
```
1
```
1. Calculate the bitwise XOR result of a set of deduplicated values:
```sql
SELECT bit_xor(DISTINCT col) FROM VALUES (3), (3), (5), (7), (null) AS tab(col);
```
Results:
```
1
```
1. Calculate the bitwise XOR result of a numerical set containing NULL values:
```sql
SELECT bit_xor(col) FROM VALUES (3), (null), (7) AS tab(col);
```
Results:
```
7
```
1. Calculate the bitwise XOR result of different data types:
```sql
SELECT bit_xor(col) FROM VALUES (TINYINT(3)), (SMALLINT(5)), (INT(7)), (BIGINT(9)) AS tab(col);
```
Results:
```
1
```
Through the above examples, it can be seen that the BIT_XOR function can be flexibly applied to different types of integer data and supports the calculation of removing duplicate values. In practical applications, this function can be used in scenarios such as encryption algorithms and checksum calculations.