使用EF從數據庫查詢是否正確？

Question

我可以問一下這是否是使用EF刪除整個數據庫表的正確方法嗎？ 部門表通過DepartmentID將Facility加入設施，部門表通過FacilityID將設施預訂加入設施，我需要從設施預訂表中刪除所有記錄。 有人可以指導我，告訴我這是否正確嗎？ 謝謝！

    db.Database.ExecuteSqlCommand(
                    "DELETE FacilityReservation FROM Department INNER JOIN Facility ON Department.DepartmentID = Facility.DepartmentID " +
                        "INNER JOIN FacilityReservation ON Facility.FacilityID = FacilityReservation.FacilityID WHERE Department.DepartmentID =" + departmentID);

Answer 1

不，當然不是，您需要從<TABLENAME>刪除，並且在進行聯接時，需要另一個“ FROM <Table>”。

您可能想要這樣：

DELETE FROM FacilityReservation 

INNER JOIN Facility 
    ON Facility.FacilityID = FacilityReservation.FacilityID 

INNER JOIN Department 
    ON Department.DepartmentID = Facility.DepartmentID 

WHERE Department.DepartmentID = @departmentID;

Answer 2

從您的SQL語句看來，可以從Facility表中檢索DepartmentID。 因此，您的SQL語句可能相當簡單，例如：

DELETE a
FROM FacilityReservation a
INNER JOIN Facility b ON a.FacilityID = b.FacilityID
WHERE b.DepartmentID = @departmentID

請參閱SQL Fiddle。