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實體框架生成以下LINQ查詢無效SQL查詢:EF6 - 使用可爲空值屬性時無效的SQL查詢(外鍵,TPH)
Car[] results = this.DbContext.Cars
.Where(x => !x.ParentId.HasValue) // also for x.ParentId == null
.ToArray();
我的ParentId屬性是可空INT,外鍵相同的表(Id屬性)。我的結果是一個空數組,但它不應該。我用類似的查詢(檢查可空屬性沒有值)使用其他表,它工作得很好。在這種情況下,區別在於ParentId是外鍵,數據庫表使用TPH。這是一個錯誤還是我犯了一些錯誤?爲什麼EF忽略可空屬性?我的配置和生成的SQL由EF(命名是隻例如,例如 「汽車」):
Context配置:
// TPH (Table per Hierarchy)
modelBuilder.Entity<Car>()
.Map<CarA>(x => x.Requires("type").HasValue(1))
.Map<CarB>(x => x.Requires("type").HasValue(2))
.Map<CarC>(x => x.Requires("type").HasValue(3))
.Map<CarD>(x => x.Requires("type").HasValue(4));
// parent child relationship
modelBuilder.Entity<Car>()
.HasMany(x => x.Children)
.WithRequired()
.HasForeignKey(child => child.ParentId);
我的類屬性:
[Column("parent_id")]
public int? ParentId { get; set; }
public virtual List<Car> Children { get; set; }
爲:
Car[] results = this.DbContext.Cars
.Where(x => !x.ParentId.HasValue)
.ToArray();
我用生成的SQL得到空結果:
SELECT
CAST(NULL AS int) AS [C1],
CAST(NULL AS int) AS [C2],
...
...
...
CAST(NULL AS decimal(18,2)) AS [C20],
CAST(NULL AS datetime2) AS [C21]
FROM (SELECT 1 AS X) AS [SingleRowTable1]
WHERE 1 = 0
但它應該是:
...
...
WHERE [Extent1].[car] IS NULL
爲:
var results = this.DbContext.Cars
.Where(x => x.ParentId.HasValue)
.ToArray();
我得到的所有實體(的ParentId被忽略)與生成的SQL:
SELECT
[Extent1].[type] AS [type],
[Extent1].[id] AS [id],
[Extent1].[parent_id] AS [parent_id],
[Extent1].[name] AS [name],
...
...
...
FROM [dbo].[car] AS [Extent1]
WHERE [Extent1].[type] IN (1,2,3,4)
測試在EF6 6.0.2/6.1.1和MS SQL Server。