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# countIf

> Example of using the countIf combinator

<h2 id="description">
  Description
</h2>

The [`If`](/reference/functions/aggregate-functions/combinators#-if) combinator can be applied to the [`count`](/reference/functions/aggregate-functions/count)
function to count the number of rows where the condition is true,
using the `countIf` aggregate combinator function.

<h2 id="example-usage">
  Example usage
</h2>

In this example, we'll create a table that stores user login attempts,
and we'll use `countIf` to count the number of successful logins.

```sql title="Query" theme={null}
CREATE TABLE login_attempts(
    user_id UInt32,
    timestamp DateTime,
    is_successful UInt8
) ENGINE = MergeTree
ORDER BY ();

INSERT INTO login_attempts VALUES
    (1, '2024-01-01 10:00:00', 1),
    (1, '2024-01-01 10:05:00', 0),
    (1, '2024-01-01 10:10:00', 1),
    (2, '2024-01-01 11:00:00', 1),
    (2, '2024-01-01 11:05:00', 1),
    (2, '2024-01-01 11:10:00', 0);

SELECT
    user_id,
    countIf(is_successful = 1) AS successful_logins
FROM login_attempts
GROUP BY user_id;
```

The `countIf` function will count only the rows where `is_successful = 1` for each user.

```response title="Response" theme={null}
   ┌─user_id─┬─successful_logins─┐
1. │       1 │                 2 │
2. │       2 │                 2 │
   └─────────┴───────────────────┘
```

<h2 id="see-also">
  See also
</h2>

* [`count`](/reference/functions/aggregate-functions/count)
* [`If combinator`](/reference/functions/aggregate-functions/combinators#-if)