> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-fix-nav-issues.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# How to Validate if Two Queries Return the Same Result-sets

> Learn how to validate that two ClickHouse queries produce identical result-sets using hash functions and comparison techniques.

## Question

How can I validate that two queries return the same resultsets?

## Answer

You can use the below approach:

```sql theme={null}
WITH
    (
        SELECT sum(cityHash64(*))
        FROM
        (
            -- your query 1 here
            -- SELECT ...
        )
    ) AS q1_resultset_hash,
    (
        SELECT sum(cityHash64(*))
        FROM
        (
            -- your query 2 here
            -- SELECT ...
        )
    ) AS q2_resultset_hash
SELECT equals(q1_resultset_hash,q2_resultset_hash) as Q1_equals_Q2
```

The example uses a [CTE](/reference/statements/select/with) to calculate sums of the [cityHash](/reference/functions/regular-functions/hash-functions#cityhash64) value of each row in these two queries and will return `1` if the two resultsets are identical.

Using some integers sequence data and some pretty formatting:

```sql theme={null}
WITH
    (
        SELECT sum(cityHash64(*))
        FROM
        (
            SELECT *
            FROM numbers(10)
            ORDER BY number DESC
        )
    ) AS q1_resultset_hash,
    (
        SELECT sum(cityHash64(*))
        FROM
        (
            SELECT *
            FROM numbers(10)
            ORDER BY number ASC
        )
    ) AS q2_resultset_hash
SELECT q1_resultset_hash = q2_resultset_hash AS Q1_equals_Q2
FORMAT Pretty
```

will return:

```
┏━━━━━━━━━━━━━━┓
┃ Q1_equals_Q2 ┃
┡━━━━━━━━━━━━━━┩
│            1 │
└──────────────┘
```

While this can be handy in many scenarios, it can't be considered as a silver bullet to validate equality of resultsets for all types and there are caveats to using it, for example if any row contains `NULL` values the above approach will fail.