Initial commit

Homework/Homework250417/Work1.sql

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+Use Homework250417
+Go
+CREATE TABLE Employee(
+    EmployeeID INT PRIMARY KEY,
+    Name NVARCHAR(20),
+    Age INT,
+    Salary INT,
+);
+Go
+/* 删除员工表信息时，如果员工个数<5，不允许删除员工信息，
+   记录下企图删除员工信息的行为 */
+CREATE TABLE DelEmployeeAttempt(
+    AttemptID INT PRIMARY KEY IDENTITY(1,1),
+    EmployeeID INT,
+    AttemptTime DATETIME DEFAULT GETDATE(),
+);
+Go
+CREATE TRIGGER trg_DelEmployee
+ON Employee
+INSTEAD OF DELETE
+AS
+BEGIN
+    DECLARE @EmployeeCount INT;
+    SELECT @EmployeeCount = COUNT(*) FROM Employee;
+    IF @EmployeeCount < 5
+    BEGIN
+        INSERT INTO DelEmployeeAttempt (EmployeeID)
+        SELECT EmployeeID FROM DELETED;
+        RAISERROR(N'少于5名员工，无法删除', 16, 1);
+    END
+    ELSE
+    BEGIN
+        DELETE FROM Employee WHERE EmployeeID IN (SELECT EmployeeID FROM DELETED);
+        PRINT(N'删除员工信息成功');
+    END
+END;
+Go