LINQ to SQL - Regroupement par heures


11

Comment regrouper le résultat d'une requête LINQ to SQL en heures, en considérant que le type de colonne est DateTime?

23

Voici une solution pour les heures techniques (sans contexte).

var query = myDC.Orders 
    .GroupBy(x => x.OrderDate.Hour) 
    .Select(g => new { 
     Hour = g.Key, 
     Amount = g.Sum(x => x.OrderAmount) 
    }); 

qui génère ceci:

SELECT SUM([t1].[OrderAmount]) AS [Amount], [t1].[value] AS [Hour] 
FROM (
    SELECT DATEPART(Hour, [t0].[OrderDate]) AS [value], [t0].[OrderAmount] 
    FROM [dbo].[Orders] AS [t0] 
    ) AS [t1] 
GROUP BY [t1].[value] 

Voici une solution pour les heures d'ouverture (contexte-FUL).

DateTime zeroDate = new DateTime(2008, 1, 1); 

var query = myDC.Orders 
    .GroupBy(x => System.Data.Linq.SqlClient.SqlMethods.DateDiffHour(zeroDate, x.OrderDate) 
    ) 
    .Select(g => new { Hours = g.Key, Amount = g.Sum(x => x.OrderAmount) }) 
    .Select(x => new { Hour = zeroDate.AddHours(x.Hours), Amount = x.Amount}); 

qui génère ceci:

SELECT DATEADD(ms, (CONVERT(BigInt,(CONVERT(Float,[t2].[value2])) * 3600000)) % 86400000, DATEADD(day, (CONVERT(BigInt,(CONVERT(Float,[t2].[value2])) * 3600000))/86400000, @p1)) AS [Hour], [t2].[value] AS [Amount] 
FROM (
    SELECT SUM([t1].[OrderAmount]) AS [value], [t1].[value] AS [value2] 
    FROM (
     SELECT DATEDIFF(Hour, @p0, [t0].[OrderDate]) AS [value], [t0].[OrderAmount] 
     FROM [dbo].[Orders] AS [t0] 
     ) AS [t1] 
    GROUP BY [t1].[value] 
    ) AS [t2] 

Ugh - que bigint/char/millisecondes choses est laid et difficile à vérifier. Je préfère faire le plus de retour sur le côté client:

var results = myDC.Orders 
    .GroupBy(x => System.Data.Linq.SqlClient.SqlMethods.DateDiffHour(zeroDate, x.OrderDate) 
    ) 
    .Select(g => new { Hours = g.Key, Amount = g.Sum(x => x.OrderAmount) }) 
    .ToList() 
    .Select(x => new { Hour = zeroDate.AddHours(x.Hours), Amount = x.Amount}); 

qui génère ceci:

SELECT SUM([t1].[OrderAmount]) AS [Amount], [t1].[value] AS [Hours] 
FROM (
    SELECT DATEDIFF(Hour, @p0, [t0].[OrderDate]) AS [value], [t0].[OrderAmount] 
    FROM [dbo].[Orders] AS [t0] 
    ) AS [t1] 
GROUP BY [t1].[value] 

Et voici une troisième façon de faire les heures contextful. Celui-ci est très convivial, mais il y a une logique de chaîne dans la base de données (beurk).

var query = myDC.Orders 
    .GroupBy(x => new DateTime(x.OrderDate.Year, x.OrderDate.Month, x.OrderDate.Day, x.OrderDate.Hour, 0, 0)) 
    .Select(g => new { Hour = g.Key, Amount = g.Sum(x => x.OrderAmount) }); 

qui génère

SELECT SUM([t1].[OrderAmount]) AS [Amount], [t1].[value] AS [Hour] 
FROM (
    SELECT CONVERT(DATETIME, (CONVERT(NCHAR(4), DATEPART(Year, [t0].[OrderDate])) + ('-' + (CONVERT(NCHAR(2), DATEPART(Month, [t0].[OrderDate])) + ('-' + CONVERT(NCHAR(2), DATEPART(Day, [t0].[OrderDate])))))) + (' ' + (CONVERT(NCHAR(2), DATEPART(Hour, [t0].[OrderDate])) + (':' + (CONVERT(NCHAR(2), @p0) + (':' + CONVERT(NCHAR(2), @p1)))))), 120) AS [value], [t0].[OrderAmount] 
    FROM [dbo].[Orders] AS [t0] 
    ) AS [t1] 
GROUP BY [t1].[value]