ClickHouse/docs/en/sql-reference/aggregate-functions/reference/groupbitmap.md

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---
toc_priority: 128
---
# groupBitmap {#groupbitmap}
Bitmap or Aggregate calculations from a unsigned integer column, return cardinality of type UInt64, if add suffix -State, then return [bitmap object](../../../sql-reference/functions/bitmap-functions.md).
``` sql
groupBitmap(expr)
```
**Parameters**
`expr` An expression that results in `UInt*` type.
**Return value**
Value of the `UInt64` type.
**Example**
Test data:
``` text
UserID
1
1
2
3
```
Query:
``` sql
SELECT groupBitmap(UserID) as num FROM t
```
Result:
``` text
num
3
```