书籍的可用性检查 [英] availability checking of books

问题描述

我正在制作一个基于Web的图书馆自动化系统，我想要一个代码来检查书籍的可用性，每本书都有自己的编号.如果发行了一些书籍而还剩下一些，那么代码将显示书籍的可用性.
我为issue_return和书制作了单独的表格，因此请在这方面指导我

I m making a web based Library automation system,I want a code for checking the availabaility of books , each book has its own id. when some books are issued and some are remaining then the code shows the availability of books.
i made separate tables for issue_return and book, so please guide me in this regard

推荐答案

如我所见:

tbl_book
--------------
ID(int)
BookISBN(varchar)
BookTitle(varchar)
等....

-负责存储有关图书的信息

tbl_issue_return
---------------------
ID(int)
BookID(int)(FK)
IssueDate(日期时间)
ReturnDate(日期时间)
等....

-负责存储已发布的书籍条目，以及是否归还书籍.


SQL获取所有可用的书:
---------------------------------
SELECT * FROM tbl_book b
在哪里
b.ID不输入(从tbl_issue_return i中选择i.ID，其中i.ReturnDate为NULL)；


SQL获取所有问题书籍(不可用的书籍)
-------------------------------------------------- --------
从tbl_issue_return i中选择i.ID，其中i.ReturnDate为NULL;

正如您对原始问题的回答所言，如果没有更多信息，我的想法可能会偏离基础.根据所提供的信息，这是我所能做出的最好的答复.另外，我并不是说这将是最有效的方法.

As I see it:

tbl_book
--------------
ID (int)
BookISBN (varchar)
BookTitle(varchar)
etc....

- responsible for storing information about books

tbl_issue_return
---------------------
ID (int)
BookID (int)(FK)
IssueDate (datetime)
ReturnDate (datetime)
etc....

- responsible for storing issued book entries, as well as wether or not the book has been returned.


SQL to get all available books:
---------------------------------
SELECT * FROM tbl_book b
WHERE
b.ID NOT IN (SELECT i.ID from tbl_issue_return i where i.ReturnDate IS NULL);


SQL to get all issues books (books that are unavailable)
----------------------------------------------------------
SELECT i.ID from tbl_issue_return i where i.ReturnDate IS NULL;

As the responses to your original question stated, without more information, my ideas could be way off base. From the information presented, this is as good of a reply as I can make. Also, I''m not claiming that this would be the most efficient means of doing this.

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