[英]Include both COUNT(*) and Sum(X) in a single async query Entity Framework
在我的 ASP.NET MVC 項目中,我試圖實現與此 SQL Server 代碼等效的代碼:
SELECT COUNT(*) as TotalCount, SUM(SomeColumn) as TotalSum
FROM SomeTable
WHERE param1 = 'foo' AND param2 = 'bar'
...在單個異步查詢中使用實體框架。 本質上,我不僅希望獲得總和,還希望獲得用於在一次調用中計算SomeColumn
列總和的行數。
到目前為止,我只在兩次調用中做到了這一點:
using (var context = new myEntities())
{
// 1st query which does .SumAsync(x => x.SomeColumn)
// 2nd query which performs a .Count() on the result set
}
是否可以在一個異步調用中執行此操作,如上面提供的 SQL? 我應該在 SQL 端創建一個視圖還是存儲過程?
var query = await (from zz in db.SomeTable
where zz.Foo > 1
group zz by 1 into grp
select new
{
rowCount = grp.CountAsync(),
rowSum = grp.SumAsync(x => x.SomeColumn)
}).ToListAsync();
我在正在運行的開發環境中測試了同步版本。
實際上沒有必要在IQueryable上調用SumAsync。 以下將以您希望的方式為您提供所需的查詢:
var foo = from item in context.Items
group item by item.ID into grp
select new
{
Value = grp.Sum(f => f.ID),
Count = grp.Count()
};
await foo.ToListAsync();
使用EF Core 6.0測試
以下LINQ查詢:
await Table.GroupBy(_ => 1, (_, rows) => new
{
Count = rows.Count()
Sum = rows.Sum(x => x.Column),
Average = rows.Average(x => x.Column),
})
.FirstOrDefaultAsync();
將轉換為以下SQL查詢:
SELECT TOP(1)
COUNT(*) AS [Count]
SUM([t].[Column]) AS [Sum],
AVG([t].[Column]) AS [Average],
FROM[Table] AS [t]
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