背景
在后端使用EFCore進行數據庫操作的時候，不可避免的要進行Group By操作，在進行Group By后有時候進行Sum的操作的時候EFCore是不能按照我們的預期生成正確的SQL的，而且這個問題EFCore的官方也沒有給出一個好的解決方式，那么在使用EFCore2.2進行開發的時候這些問題又不可避免，那么我們該如何規避這個問題，並且使之生成我們期望的SQL語句呢，本篇我們我們就這個出現這個問題的現象以及解決方案來進行分析，來看看在現階段到底該如何解決這個問題。
正常情況
我們先來看一下能夠正常生成SQL的EFCore的寫法，這種情況下會生成符合預期的SQL語句並且沒有什么問題，我們先來看看正常情況的EFCore的代碼。
/// <summary>
/// 查詢月度輔導任務清單列表
/// </summary>
/// <param name="input">查詢輸入</param>
/// <param name="pageRequest">分頁請求</param>
/// <returns>帶分頁的月度任務清單</returns>
public async Task<Page<GetCoachTaskDetailOutput>> GetCoachTaskDetailExAsync(GetCoachTaskDetailInput input, PageRequest pageRequest) {
var queryResults = from v in from coachTask in _coachTaskRepository.GetAll()
.WhereIf(!string.IsNullOrWhiteSpace(input.Code), c => c.Code.Contains(input.Code))
.WhereIf(input.Year.HasValue, c => c.Year == input.Year)
.WhereIf(input.Quarter.HasValue, c => c.Quarter == input.Quarter)
.WhereIf(input.Month.HasValue, c => c.Month == input.Month)
.WhereIf(!string.IsNullOrWhiteSpace(input.MarketingResponsibleName),
c => c.MarketingResponsibleName.Contains(input.MarketingResponsibleName))
.WhereIf(input.MarketingDepartmentIds.Any(), c => input.MarketingDepartmentIds.Contains(c.MarketingDepartmentId))
join coachTaskDetail in _coachTaskDetailRepository.GetAll()
.WhereIf(!string.IsNullOrWhiteSpace(input.DealerCode), d => d.DealerCode.Contains(input.DealerCode))
.WhereIf(input.Status.Any(), d => input.Status.Contains(d.Status))
.WhereIf(input.ReviewStatus.HasValue, d => d.ReviewStatus == input.ReviewStatus)
.WhereIf(input.BeginActualCoachTime.HasValue, d => input.BeginActualCoachTime <= d.ActualCoachTime)
.WhereIf(input.EndActualCoachTime.HasValue, d => d.ActualCoachTime <= input.EndActualCoachTime)
on coachTask.Id equals coachTaskDetail.CoachTaskId
join coachTaskItemDetail in _coachTaskItemDetailRepository.GetAll()
.WhereIf(input.Type.HasValue, i => i.Type == input.Type)
on coachTaskDetail.Id equals coachTaskItemDetail.CoachTaskDetailId
select new {
coachTaskDetail.Id,
coachTask.Code,
coachTask.Year,
coachTask.Quarter,
coachTask.Month,
coachTaskDetail.DealerCode,
coachTaskDetail.DealerName,
coachTaskDetail.Status,
coachTaskDetail.ReviewStatus,
coachTask.MarketingDepartmentName,
coachTask.MarketingResponsibleName,
coachTaskDetail.ActualerCoachName,
coachTaskDetail.ActualCoachTime,
coachTaskItemDetail.StandardScore,
coachTaskItemDetail.IsQualified
}
group v by new {
v.Id,
v.Code,
v.Year,
v.Quarter,
v.Month,
v.DealerCode,
v.DealerName,
v.Status,
v.ReviewStatus,
v.MarketingDepartmentName,
v.MarketingResponsibleName,
v.ActualerCoachName,
v.ActualCoachTime,
} into tempGroups
select new GetCoachTaskDetailGroupByResultModel {
Id = tempGroups.Key.Id,
Code = tempGroups.Key.Code,
Year = tempGroups.Key.Year,
Quarter = tempGroups.Key.Quarter,
Month = tempGroups.Key.Month,
DealerCode = tempGroups.Key.DealerCode,
DealerName = tempGroups.Key.DealerName,
Status = tempGroups.Key.Status,
ReviewStatus = tempGroups.Key.ReviewStatus,
MarketingDepartmentName = tempGroups.Key.MarketingDepartmentName,
MarketingResponsibleName = tempGroups.Key.MarketingResponsibleName,
ActualerCoachName = tempGroups.Key.ActualerCoachName,
ActualCoachTime = tempGroups.Key.ActualCoachTime,
//對應的月度輔導任務項目清單中標准分值
ScoreTotal = tempGroups.Sum(r => r.StandardScore ?? 0),
NoQualifiedQty = tempGroups.Sum(r => r.IsQualified == false ? 1 : 0)
};
//獲取分組后的結果
var totalCount = await queryResults.CountAsync();
var pagedResults = await queryResults.ProjectTo<GetCoachTaskDetailOutput>(_autoMapper.ConfigurationProvider).PageAndOrderBy(pageRequest).ToListAsync();
pagedResults.ForEach(item => {
if (item.ScoreTotal < 0) {
item.ScoreTotal = 0;
}
});
return new Page<GetCoachTaskDetailOutput>(pageRequest, totalCount, pagedResults);
}
上面的寫法非常簡單就是三張表進行join然后進行分組，只不過是最終的結果中ScoreTotal和NoQualifiedQty需要根據分組的結果進行求和，對於這種比較簡單的分組結果EFCore是完全能夠生成正確的SQL,我們來看看此時EFCore正確生成的SQL。
SELECT TOP (20)
[coachTaskDetail].[ActualCoachTime],
[coachTaskDetail].[ActualerCoachName],
[coachTask].[Code],
[coachTaskDetail].[DealerCode],
COALESCE([coachTaskDetail].[Id], '00000000-0000-0000-0000-000000000000') AS [Id],
[coachTask].[MarketingDepartmentName],
[coachTask].[MarketingResponsibleName],
[coachTask].[Month],
COALESCE(SUM(CASE
WHEN [coachTaskItemDetail].[IsQualified] = 0
THEN 1
ELSE 0
END), 0) AS [NoQualifiedQty],
[coachTask].[Quarter],
COALESCE([coachTaskDetail].[ReviewStatus], 0) AS [ReviewStatus],
COALESCE(SUM(COALESCE([coachTaskItemDetail].[StandardScore], 0.0)), 0.0) AS [ScoreTotal],
[coachTaskDetail].[DealerName] AS [ShortName],
COALESCE([coachTaskDetail].[Status], 0) AS [Status],
COALESCE([coachTask].[Year], 0) AS [Year]
FROM [CoachTask] AS [coachTask]
INNER JOIN [CoachTaskDetail] AS [coachTaskDetail] ON [coachTask].[Id] = [coachTaskDetail].[CoachTaskId]
INNER JOIN [CoachTaskItemDetail] AS [coachTaskItemDetail]
ON [coachTaskDetail].[Id] = [coachTaskItemDetail].[CoachTaskDetailId]
GROUP BY [coachTaskDetail].[Id], [coachTask].[Code], [coachTask].[Year], [coachTask].[Quarter], [coachTask].[Month],
[coachTaskDetail].[DealerCode], [coachTaskDetail].[DealerName], [coachTaskDetail].[Status],
[coachTaskDetail].[ReviewStatus], [coachTask].[MarketingDepartmentName], [coachTask].[MarketingResponsibleName],
[coachTaskDetail].[ActualerCoachName], [coachTaskDetail].[ActualCoachTime]
ORDER BY [coachTask].[Code] DESC
未完，待續......