USE Homework250417
Go
/* 某公司想举行一个小型的联谊会，关系Male记录注册的男宾信息，关系Female记录注册的女宾信息。
   建立一个触发器，将来宾的人数现在在50人以内。 */
CREATE TABLE Male(
    ID INT PRIMARY KEY IDENTITY(1,1),
    Name NVARCHAR(20) NOT NULL,
);
CREATE TABLE Female(
    ID INT PRIMARY KEY IDENTITY(1,1),
    Name NVARCHAR(20) NOT NULL,
);
Go
CREATE TRIGGER trg_LimitGuestCount_Male
ON Male
INSTEAD OF INSERT
AS
BEGIN
    DECLARE @MaleCount INT;
    DECLARE @FemaleCount INT;
    DECLARE @TotalCount INT;
    SELECT @MaleCount = COUNT(*) FROM Male;
    SELECT @FemaleCount = COUNT(*) FROM Female;
    SET @TotalCount = @MaleCount + @FemaleCount;
    IF @TotalCount >= 50
        RAISERROR(N'宾客人数已满，无法添加更多男宾', 16, 1)
    ELSE
    BEGIN
        INSERT INTO Male (Name)
        SELECT Name FROM INSERTED;
        PRINT(N'添加男宾信息成功');
    END
END;
Go
CREATE TRIGGER trg_LimitGuestCount_Female
    ON Female
    INSTEAD OF INSERT
    AS
    BEGIN
        DECLARE @MaleCount INT;
        DECLARE @FemaleCount INT;
        DECLARE @TotalCount INT;
        SELECT @MaleCount = COUNT(*) FROM Male;
        SELECT @FemaleCount = COUNT(*) FROM Female;
        SET @TotalCount = @MaleCount + @FemaleCount;
        IF @TotalCount >= 50
            RAISERROR(N'宾客人数已满，无法添加更多女宾', 16, 1)
        ELSE
        BEGIN
            INSERT INTO Female (Name)
            SELECT Name FROM INSERTED;
            PRINT(N'添加女宾信息成功');
        END
    END;
Go
-- Test