TransactSQL selectCourse storedprocedurestuSysInfo project form cmm

选课存储过程业务逻辑

course 表和student 表,student_course表

student不能重复选课

student选课时间（timeRange字段）不能有冲突

上代码：

CREATE PROCEDURE [dbo].[selectCourse](
@course_id int ,
@student_id int ,
@result int output
)
AS
BEGIN
SET NOCOUNT ON;
    IF(EXISTS(SELECT * FROM [student_course] WHERE [course_id] = @course_id AND [student_id] = @student_id))
    BEGIN
    set @result = 0;
    --RETURN 12;--已经选择了该课程
    END
    ELSE IF(EXISTS(SELECT * FROM [student_course] WHERE [student_id] = @student_id))
    BEGIN
        --print 'ss'
        declare @courseid int,@timerange int,@timerangetoinsert int;    
        SELECT @timerangetoinsert=timeRange FROM [course] where id = @course_id;
        --print @timerangetoinsert;
        DECLARE selectedcourse_cursor CURSOR FOR
        select sc.course_id,c.timeRange from [student_course] as sc inner join course as c on c.id = sc.course_id where [student_id] = @student_id;
        
        OPEN selectedcourse_cursor;
        
        -- Perform the first fetch and store the values in variables.
        -- Note: The variables are in the same order as the columns
        -- in the SELECT statement. 

        FETCH NEXT FROM selectedcourse_cursor
        INTO @courseid,@timerange;

        -- Check @@FETCH_STATUS to see if there are any more rows to fetch.
        WHILE @@FETCH_STATUS = 0
        BEGIN
            IF(@timerangetoinsert<>@timerange)
                BEGIN
                INSERT INTO [student_course](course_id,student_id)VALUES(@course_id,@student_id);
                set @result = 1;--选课成功
                BREAK;--选课成功
                END
            ELSE 
            BEGIN
                set @result = 2;--时间冲突
                BREAK;
            END

        -- This is executed as long as the previous fetch succeeds.
        FETCH NEXT FROM selectedcourse_cursor
        INTO @courseid,@timerange;
        END

        CLOSE selectedcourse_cursor;
        DEALLOCATE selectedcourse_cursor;
    END
    ELSE 
    BEGIN
        INSERT INTO [student_course](course_id,student_id)VALUES(@course_id,@student_id);
        set @result = 1;--选课成功
    END
RETURN @result;
END