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+# 图书管理系统
+
+```mysql
+create database book_admin;
+use book_admin;
+CREATE TABLE `admin` (
+  `admin_id` int NOT NULL AUTO_INCREMENT,
+  `admin_name` char(5) DEFAULT NULL,
+  PRIMARY KEY (`admin_id`)
+) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb3;
+
+CREATE TABLE `admin_to_book_type` (
+  `book_type_id` int NOT NULL AUTO_INCREMENT,
+  `type_name` varchar(10) DEFAULT NULL,
+  `admin_id` int DEFAULT NULL,
+  PRIMARY KEY (`book_type_id`),
+  KEY `admin_id` (`admin_id`),
+  CONSTRAINT `admin_to_book_type_ibfk_1` FOREIGN KEY (`admin_id`) REFERENCES `admin` (`admin_id`)
+) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb3;
+
+CREATE TABLE `author_info` (
+  `author_id` int NOT NULL AUTO_INCREMENT,
+  `author_name` varchar(10) DEFAULT NULL,
+  `author_age` char(5) DEFAULT NULL,
+  `author_address` varchar(10) DEFAULT NULL,
+  `book_id` int DEFAULT NULL,
+  PRIMARY KEY (`author_id`),
+  KEY `book_id` (`book_id`),
+  CONSTRAINT `author_info_ibfk_1` FOREIGN KEY (`book_id`) REFERENCES `book_info` (`book_id`)
+) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb3;
+
+CREATE TABLE `book_info` (
+  `book_id` int NOT NULL AUTO_INCREMENT,
+  `book_name` varchar(10) DEFAULT NULL,
+  `book_number` varchar(10) DEFAULT NULL,
+  `book_status` char(2) DEFAULT NULL,
+  `book_type_id` int DEFAULT NULL,
+  PRIMARY KEY (`book_id`),
+  KEY `book_type_id` (`book_type_id`),
+  CONSTRAINT `book_info_ibfk_1` FOREIGN KEY (`book_type_id`) REFERENCES `admin_to_book_type` (`book_type_id`)
+) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8mb3;
+
+
+
+SELECT admin.admin_id, admin.admin_name, admin_to_book_type.book_type_id, admin_to_book_type.type_name, book_info.book_id, book_info.book_name, book_info.book_number, book_info.book_status, author_info.author_id, author_info.author_name, author_info.author_age, author_info.author_address
+FROM admin
+LEFT JOIN admin_to_book_type ON admin.admin_id = admin_to_book_type.admin_id
+LEFT JOIN book_info ON admin_to_book_type.book_type_id = book_info.book_type_id
+LEFT JOIN author_info ON book_info.book_id = author_info.book_id;
+```
+
+![image-20230910222208203](https://gitee.com/fang-zengxing/database-advanced/raw/master/image-20230910222208203.png)
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