SQL - How to Get Record Count for Each Day of the Week

In this article, we will explore how to get record counts for each day of the week. We’ll start by understanding the current query, its limitations, and then dive into a revised solution that addresses these issues.

Understanding the Current Query

The original query aims to retrieve records from SmartTappScanLog that fall within the current week, starting on Monday. The query uses DATEADD and DATEPART functions to calculate the first day of the week as Monday.

SET DATEFIRST 1 -- Beginning of week is Monday
SELECT DateTime, ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DateTime >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DateTime <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  ORDER BY DateTime ASC

However, the query has a few issues that prevent it from achieving the desired result. We’ll address each of these in subsequent sections.

Issues with the Current Query

Incorrect Order of Group By and Order By

In SQL Server, GROUP BY must come before ORDER BY. The original query attempts to group records by DateTime but places the GROUP BY clause after ORDER BY, which results in a syntax error near GROUP.

SELECT Count(DateTime), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DateTime >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DateTime <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY DateTime
  ORDER BY DateTime ASC

To fix this issue, we need to reorder the clauses to place GROUP BY before ORDER BY.

Non-Aggregated Columns in Group By

In SQL Server, when using GROUP BY, all non-aggregated columns must also be included in the group by clause. In the original query, only DateTime is used for grouping.

SELECT Count(DateTime), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DateTime >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DateTime <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY DateTime

To resolve this issue, we must add the non-aggregated columns ScanPoints and PostPoints to the group by clause.

Incorrect Data Type for Column DateTime

The column DateTime is likely to contain a date and time value. However, in the original query, it’s being used as if it only contains a date value. This might lead to unexpected results when grouping by this column.

To fix this issue, we can convert the DateTime column to a date type before grouping.

Revised Solution

Let’s address each of the issues mentioned above and provide a revised solution that achieves the desired result.

Correct Order of Group By and Order By

SELECT Count(DateTime), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DateTime >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DateTime <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY ScanPoints, PostPoints
  ORDER BY ScanPoints ASC, PostPoints ASC

Non-Aggregated Columns in Group By

By adding ScanPoints and PostPoints to the group by clause, we ensure that these columns are included when grouping records.

SELECT Count(DateTime), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DateTime >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DateTime <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY ScanPoints, PostPoints

Incorrect Data Type for Column DateTime

To ensure accurate results when grouping by DateTime, we can convert it to a date type before grouping.

SELECT Count(DATETIME_column), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DATETIME_column >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DATETIME_column <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY DATETIME_column

However, the revised query above still has an issue. When grouping by DateTime_column, we must also include non-aggregated columns in the group by clause.

SELECT Count(DATETIME_column), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DATETIME_column >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DATETIME_column <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY DATETIME_column, ScanPoints, PostPoints

This revised query ensures that all non-aggregated columns are included when grouping records.

Additional Issue: Data Type Conversion

When grouping by DateTime, it’s essential to convert it to a date type before grouping. This can be achieved using the DATE function in SQL Server.

SELECT Count(DATE(DateTime_column)), ScanPoints, PostPoints 
FROM SmartTappScanLog
WHERE DateTime_column >= dateadd(day, 1-datepart(dw, getdate()), CONVERT(date,getdate())) 
  AND DateTime_column <  dateadd(day, 8-datepart(dw, getdate()), CONVERT(date,getdate()))
  AND UserID = '1' AND BeerID = '3'
  GROUP BY DATE(DateTime_column), ScanPoints, PostPoints

This revised query converts the DateTime column to a date type before grouping and ensures accurate results.

Conclusion

In conclusion, the revised solution addresses all issues with the original query, including incorrect order of group by and order by, non-aggregated columns in group by, and data type conversion. By following this revised approach, you can achieve your desired result when retrieving records from SmartTappScanLog that fall within the current week, starting on Monday.

Last modified on 2024-12-16