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Q&A How to easily support time frame grouping in queries?

In SQL Server 2022+, there's a dedicated binning function called DATE_BUCKET. Each of these statements increments DATE_BUCKET with a bucket width of 1 from the origin time: DECLARE @date DATETI...

posted 1mo ago by Michael‭ · edited 1mo ago by Michael‭

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#2: Post edited by

Michael‭ · 2024-03-29T18:20:39Z (about 1 month ago)
Fix pseudocode sample in case of multiple answers per question.

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In SQL Server 2022+, there's a dedicated binning function [called `DATE_BUCKET`][date_bucket].
> Each of these statements increments `DATE_BUCKET` with a bucket width of `1` from the origin time:
>
> ```sql
> DECLARE @date DATETIME2 = '2020-04-30 21:21:21';
> SELECT 'Week', DATE_BUCKET(WEEK, 1, @date)
> UNION ALL
> SELECT 'Day', DATE_BUCKET(DAY, 1, @date)
> UNION ALL
> SELECT 'Hour', DATE_BUCKET(HOUR, 1, @date)
> UNION ALL
> SELECT 'Minutes', DATE_BUCKET(MINUTE, 1, @date)
> UNION ALL
> SELECT 'Seconds', DATE_BUCKET(SECOND, 1, @date);
> ```
> Here's the result set.
>
> | | |
> |-|-|
> | Week | 2020-04-27 00:00:00.0000000 |
> | Day | 2020-04-30 00:00:00.0000000 |
> | Hour | 2020-04-30 21:00:00.0000000 |
> | Minutes | 2020-04-30 21:21:00.0000000 |
> | Seconds | 2020-04-30 21:21:21.0000000 |
In older versions of SQL Server, [I did date binning][so] with `DATEADD` and `DATEDIFF`, rather than offsetting integers or casting to a string.
Taking your second faux-CTE temporary table, it would look like this:
```sql
SELECT DATEADD(MONTH, FLOOR(DATEDIFF(MONTH, '2000', q.CreationDate)), '2000') AS bin,
COUNT(1) Cnt
INTO #q_cte
FROM Posts AS q
INNER JOIN Users AS qu
ON qu.Id = q.OwnerUserId
AND qu.Reputation >= 1000
~~WHERE q.CreationDate BETWEEN '20190101' AND '20210301'~~
~~AND q.PostTypeId = 1~~
GROUP BY DATEDIFF(MONTH, '2000', q.CreationDate)
```
~~I'm not sure if it's faster, but I think you could write your query with a single pass through Questions, recording whether each one is answered or not, and group those.~~
```sql
~~SELECT DATEADD(MONTH, ...) AS bin,~~
~~COALESCE((SELECT 1 FROM ...), 0) AS is_answered,~~
~~q.ID~~
INTO #q_cte
FROM Posts AS q
WHERE ...;
SELECT bin, 100. * SUM(is_answered) / COUNT(*) AS ratio
FROM #q_cte
GROUP BY bin
```
[date_bucket]: https://learn.microsoft.com/en-us/sql/t-sql/functions/date-bucket-transact-sql?view=sql-server-ver16
[so]: https://stackoverflow.com/a/41944083/241211

In SQL Server 2022+, there's a dedicated binning function [called `DATE_BUCKET`][date_bucket].
> Each of these statements increments `DATE_BUCKET` with a bucket width of `1` from the origin time:
>
> ```sql
> DECLARE @date DATETIME2 = '2020-04-30 21:21:21';
> SELECT 'Week', DATE_BUCKET(WEEK, 1, @date)
> UNION ALL
> SELECT 'Day', DATE_BUCKET(DAY, 1, @date)
> UNION ALL
> SELECT 'Hour', DATE_BUCKET(HOUR, 1, @date)
> UNION ALL
> SELECT 'Minutes', DATE_BUCKET(MINUTE, 1, @date)
> UNION ALL
> SELECT 'Seconds', DATE_BUCKET(SECOND, 1, @date);
> ```
> Here's the result set.
>
> | | |
> |-|-|
> | Week | 2020-04-27 00:00:00.0000000 |
> | Day | 2020-04-30 00:00:00.0000000 |
> | Hour | 2020-04-30 21:00:00.0000000 |
> | Minutes | 2020-04-30 21:21:00.0000000 |
> | Seconds | 2020-04-30 21:21:21.0000000 |
In older versions of SQL Server, [I did date binning][so] with `DATEADD` and `DATEDIFF`, rather than offsetting integers or casting to a string.
Taking your second faux-CTE temporary table, it would look like this:
```sql
SELECT DATEADD(MONTH, FLOOR(DATEDIFF(MONTH, '2000', q.CreationDate)), '2000') AS bin,
COUNT(1) Cnt
INTO #q_cte
FROM Posts AS q
INNER JOIN Users AS qu
ON qu.Id = q.OwnerUserId
AND qu.Reputation >= 1000
WHERE q.CreationDate BETWEEN '20190101' AND '20210301'
AND q.PostTypeId = 1
GROUP BY DATEDIFF(MONTH, '2000', q.CreationDate)
```
I'm not sure if it's faster, but I think you could write your query with a single pass through the Question posts. Record whether each one is answered or not, and group those.
```sql
SELECT q.ID, -- Not actually necessary. Just a helpful check.
DATEADD(MONTH, ...) AS bin,
COALESCE((SELECT TOP(1) 1 FROM ...), 0) AS is_answered
INTO #q_cte
FROM Posts AS q
WHERE ...;
SELECT bin, 100. * SUM(is_answered) / COUNT(*) AS ratio
FROM #q_cte
GROUP BY bin
```
[date_bucket]: https://learn.microsoft.com/en-us/sql/t-sql/functions/date-bucket-transact-sql?view=sql-server-ver16
[so]: https://stackoverflow.com/a/41944083/241211

#1: Initial revision by

Michael‭ · 2024-03-29T16:03:02Z (about 1 month ago)

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In SQL Server 2022+, there's a dedicated binning function [called `DATE_BUCKET`][date_bucket].

> Each of these statements increments `DATE_BUCKET` with a bucket width of `1` from the origin time:
>
> ```sql
> DECLARE @date DATETIME2 = '2020-04-30 21:21:21';
> SELECT 'Week', DATE_BUCKET(WEEK, 1, @date)
> UNION ALL
> SELECT 'Day', DATE_BUCKET(DAY, 1, @date)
> UNION ALL
> SELECT 'Hour', DATE_BUCKET(HOUR, 1, @date)
> UNION ALL
> SELECT 'Minutes', DATE_BUCKET(MINUTE, 1, @date)
> UNION ALL
> SELECT 'Seconds', DATE_BUCKET(SECOND, 1, @date);
> ```
> Here's the result set.
>
> | | |
> |-|-|
> | Week    | 2020-04-27 00:00:00.0000000 |
> | Day     | 2020-04-30 00:00:00.0000000 |
> | Hour    | 2020-04-30 21:00:00.0000000 |
> | Minutes | 2020-04-30 21:21:00.0000000 |
> | Seconds | 2020-04-30 21:21:21.0000000 |

In older versions of SQL Server, [I did date binning][so] with `DATEADD` and `DATEDIFF`, rather than offsetting integers or casting to a string.

Taking your second faux-CTE temporary table, it would look like this:

```sql
SELECT  DATEADD(MONTH, FLOOR(DATEDIFF(MONTH, '2000', q.CreationDate)), '2000') AS bin, 
        COUNT(1) Cnt
INTO    #q_cte
FROM    Posts AS q
        INNER JOIN  Users AS qu
                    ON qu.Id = q.OwnerUserId
                    AND qu.Reputation >= 1000
WHERE q.CreationDate BETWEEN '20190101' AND '20210301'
      AND q.PostTypeId = 1
GROUP BY DATEDIFF(MONTH, '2000', q.CreationDate)
```

I'm not sure if it's faster, but I think you could write your query with a single pass through Questions, recording whether each one is answered or not, and group those.

```sql
SELECT  DATEADD(MONTH, ...) AS bin,
        COALESCE((SELECT 1 FROM ...), 0) AS is_answered,
        q.ID
INTO    #q_cte
FROM    Posts AS q
WHERE   ...;

SELECT  bin, 100. * SUM(is_answered) / COUNT(*) AS ratio
FROM    #q_cte
GROUP BY bin
```

[date_bucket]: https://learn.microsoft.com/en-us/sql/t-sql/functions/date-bucket-transact-sql?view=sql-server-ver16
[so]: https://stackoverflow.com/a/41944083/241211

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