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> Reference material for BIT_AND

# BIT_AND

Performs a bitwise `AND` operation on an integer expression, ignoring null input values. Bitwise `AND` compares two bits and returns `1` if both are `1`, and `0` otherwise.

Numbers are represented in two's complement, a binary method for signed integers as follows:

* Positive numbers are represented in standard binary form, while negative numbers are derived by inverting the bits of their positive counterpart and adding `1`.
* A leftmost bit of `0` indicates a positive number, while `1` indicates a negative number.

## Syntax

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
BIT_AND([ DISTINCT ] <expression>) [FILTER ([WHERE] <condition>)]
```

Note: `DISTINCT` has no effect on the function's result.

## Parameters

| Parameter      | Description                                                       | Supported input types |
| :------------- | :---------------------------------------------------------------- | :-------------------- |
| `<expression>` | The expression used to compute the result.                        | `INT`, `BIGINT`       |
| `<condition>`  | An optional boolean expression to filter rows used in aggregation | `BOOL`                |

## Return Types

The `BIT_AND` function returns a result of either type `INT` or `BIGINT`, depending on the type of the input.

## Examples

**Example**

The following code example performs a bitwise `AND` operation across all integers ranging from `1` to `3`:

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT BIT_AND(a)
FROM GENERATE_SERIES(1, 3) as a;
```

**Returns**

The previous code example returns `0`. In a 4-bit system, the binary representation of integers from `1` to `3` is:

* `1` `->` `0001`
* `2` `->` `0010`
* `3` `->` `0011`

The bitwise `AND` function returns `0` because there is no bit position where all three integers have a `1`. The bitwise `AND` of `0001` and `0010` is `0000`, which equals `0`. The bitwise `AND` between `0000` and `0011` is `0000`, or `0`.

**Example**

The following code performs a bitwise `AND` operation across two rows in column `a` that contain the values `-1` and `3`, respectively:

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT BIT_AND(a)
FROM UNNEST([-1,3]) as a;
```

**Returns**

The previous code example returns `3`. In a 4-bit system, the binary representation of `-1` and `3` is:

* `-1` `->` `1111`
* `3` `->` `0011`

The bitwise `AND` of `1111` and `0011` is `0011` because the last two positions have `1` in both values.