Question

CREATE TABLE PersonTask
(
PersonId INT NOT NULL,
WeekId INT NOT NULL,
WeekDaysTaskId INT,
WeekEndTaskId INT
)
GO
CREATE TABLE Task
(
Id INT PRIMARY KEY,
[Description] VARCHAR(250) NOT NULL
)
GO
INSERT INTO Task(Id, [Description]) VALUES(1, 'Task-01')
INSERT INTO Task(Id, [Description]) VALUES(2, 'Task-02')
INSERT INTO Task(Id, [Description]) VALUES(3, 'Task-03')
GO
INSERT INTO PersonTask(PersonId, WeekId, WeekDaysTaskId, WeekEndTaskId) VALUES(1, 1, NULL, 1)
INSERT INTO PersonTask(PersonId, WeekId, WeekDaysTaskId, WeekEndTaskId) VALUES(1, 2, 2, NULL)
INSERT INTO PersonTask(PersonId, WeekId, WeekDaysTaskId, WeekEndTaskId) VALUES(1, 3, 3, 3)
GO

SELECT 
        PT.PersonId, 
        WeekId,
        'Not on Bench' as [Status]
    FROM PersonTask AS PT
    INNER JOIN Task AS T ON T.Id IN (PT.WeekDaysTaskId, PT.WeekEndTaskId)
    WHERE WeekId = 3/*Param-1*/ and PersonId = 1/*Param-2*/

我正在尝试编写一个等同于上述T-sql语句的linq查询但是徒劳无功。有人可以帮助C＃Linq查询获取上述T-SQL语句。

Answer 1

必须是这样的（假设你有personTaskQueryable和taskQueryable）：

from pt in personTaskQueryable
from t in taskQueryable
where (t.Id == pt.WeekDaysTaskId || t.Id == pt.WeekEndTaskId)
    && pt.WeekId == 3 && pt.PersonId == 1
select new { pt.PersonId, pt.WeekId, Status = "Not on Bench" }

我没有尝试，因为我直接在答案文本框中编码，但Linq文档说你不能用“join”操作符来做这些事情，因为它只支持equijoins。

解决方案是首先构建笛卡尔积并从那里限制结果集。

Linq等效语句用于SQL内部连接和IN语句

1 个答案: