触发从 table 中删除记录（如果存在）

Question

我有以下 table 和 table employee_assignment_future，它们具有相同的列。

CREATE TABLE dbo.employee_assignment (
    employee_id BIGINT,
    department_id BIGINT,
    job_title_id BIGINT,
    manager_id BIGINT,
    effective_start_date SMALLDATETIME,
    effective_end_date SMALLDATETIME,
    action_code VARCHAR(60)
);

我需要一个触发器来检查 employee_id 和 department_id 以及 job_title_id 和 manager_id 是否存在于 employee_assignment_future 每当来自 [=19 的记录时=] 已更新，如果是，则将其从 employee_assignment_future 中删除。这 4 个 ID 是外键。

我想到了这样的东西：

CREATE OR ALTER TRIGGER t_v_employee_assignment_update3 on employee_assignment
AFTER UPDATE
AS
BEGIN           
    DECLARE @emp_id BIGINT = (SELECT employee_id from inserted)
    DECLARE @dep_id BIGINT = (SELECT department_id from inserted)
    DECLARE @job_id BIGINT = (SELECT job_title_id from inserted)
    DECLARE @man_id BIGINT = (SELECT manager_id from inserted)

    
    DELETE FROM employee_assignment_future
    WHERE @emp_id = employee_assignment_future.employee_id 
    AND @dep_id = employee_assignment_future.department_id
    AND @job_id = employee_assignment_future.job_title_id
    AND @man_id = employee_assignment_future.manager_id
END;

SELECT * FROM employee_assignment_future
SELECT * FROM employee_assignment

UPDATE employee_assignment
SET employee_id = 4, department_id = 2, job_title_id = 8, manager_id = 3, effective_start_date ='2019-11-13 00:00:00', effective_end_date = NULL, action_code = NULL
WHERE employee_id = 64;

但是，它不会从 employee_assignment_future 中删除任何内容，也不会更新 employee_assignment 中的任何内容。

Answer 1

一个简单的DELETE + JOIN 应该检测记录是否存在，然后可以删除。

下面的删除可以是你触发器的整个主体。

    DELETE F
    FROM employee_assignment_future F
    INNER JOIN Inserted I
        ON I.employee_id = F.employee_id 
        AND I.department_id = F.department_id
        AND I.job_title_id = F.job_title_id
        AND I.manager_id = F.manager_id;

注意：您不能假设 Inserted（或 Deleted）只有一行。您需要使用基于集合的操作并处理它有 0-N 行。

触发从 table 中删除记录（如果存在）

Trigger to delete the record from the table if it exists in it

sql

sql-server

triggers

sql-server-2019