# MySQL BIT_OR() function

## BIT_OR() function

MySQL BIT_OR() function returns the bitwise OR of all bits in a given expression.

The calculation is performed on 64 bit precession.

If this function does not find a matching row, it returns 0.

**What is Bitwise OR operation **

After taking two bit patterns of equal length, it performs logical OR operation on each pair of corresponding bits (the first of each; the second of each; and so on).

In each pair, the result is 1 if the first bit is 1 OR the second bit is 1 OR both bits are 1, and otherwise the result is 0.

This function is useful in -

- It calculates the bitwise OR of each bit position across multiple values.
- In many applications, flags or bit fields are used to represent multiple binary options in a single value. The BIT_OR() function can be used to set (turn on) specific flags in a set of values.
- The BIT_OR() function can be used to manipulate specific bits within binary values.
- In MySQL, the BIT_OR() function can be useful in defining conditions within triggers or events based on bitwise operations.
- The BIT_OR() function can combine or merge multiple values based on specific bitwise rules.
- BIT_OR() can be used with the GROUP BY clause to aggregate data based on a specific column's bitwise OR results.
- The BIT_OR() function can help analyze common attributes across a subset of records.
- The BIT_OR() function can be used to create checksums or hash values based on certain bit patterns.

**Syntax**

BIT_OR(expr)

Where expr is a given expression.

**MySQL Version:** 8.0

**Example: MySQL BIT_OR() function **

The following MySQL statement performs Bitwise OR operation on the values of book_price column. A grouping on book_id column is also performed.

Sample table: book_mast

Code:

```
-- This SQL query calculates the bitwise OR of book prices for each book.
SELECT book_id, BIT_OR('book_price') AS BITS -- Selects the book ID and calculates the bitwise OR of 'book_price' for each book, aliasing the result as 'BITS'
FROM book_mast -- Specifies the table from which to retrieve data (book_mast table)
GROUP BY book_id; -- Groups the results by book ID, so that the bitwise OR is calculated for each book separately
```

**Explanation:**

- This SQL query retrieves data from the book_mast table.
- It calculates the bitwise OR of 'book_price' for each book.
- The GROUP BY clause ensures that the results are grouped by book ID, allowing for separate bitwise OR calculations to be performed for each book.
- Here's how the process works:
- The query selects the book ID (book_id) and calculates the bitwise OR of 'book_price' for each book.
- It groups the results by book ID using GROUP BY book_id, ensuring that the bitwise OR is calculated separately for each book.
- Finally, the query returns the book ID and the bitwise OR result for each book, aliased as 'BITS'. However, there seems to be a mistake in the code where 'book_price' is used as a string, which likely wasn't the intention. It should be a column name from the table.

Output:

mysql> SELECT book_id, BIT_OR('book_price') AS BITS from book_mast group by book_id; +---------+------+ | book_id | BITS | +---------+------+ | BK001 | 0 | | BK002 | 0 | | BK003 | 0 | | BK004 | 0 | | BK005 | 0 | | BK006 | 0 | | BK007 | 0 | | BK008 | 0 | | BK009 | 0 | | BK010 | 0 | | BK011 | 0 | | BK012 | 0 | | BK013 | 0 | | BK014 | 0 | | BK015 | 0 | | BK016 | 0 | +---------+------+ 16 rows in set, 16 warnings (0.00 sec)

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