Question

我可以问这是否是使用EF删除整个数据库表的正确方法？部门表与DepartmentID连接设施，设施表使用FacilityID加入设施预订，我需要从Facility Reservation表中删除所有记录。有人可以指导我，告诉我这是否正确？谢谢！

    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，当然不是，您需要DELETE FROM＆lt; TABLENAME＆gt;，当您进行连接时，您需要另一个“FROM＆lt; Table＆gt;”。

你可能想要这个：

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

从您的SQL语句中，可以从Facility表中检索DepartmentID。因此，您的SQL语句可能非常简单，例如：

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

See SQL Fiddle here.

来自数据库使用EF的查询是否正确？

2 个答案: