数据库代写、database作业代写的课程作业一天比一天繁重，这些学生不只是要求深刻理解专业课的学科知识，还要学会熟练应用。作为最卷的一代，学习压力可以说是很大了。当你遇到无法攻克的课业难题是，数据库代写服务能在很大程度上缓解同学们的焦虑。
找数据库代写时应该注意什么？
(1)行业经验
由于代写机构比较多，其中有一部分机构具有较久的代写年限，丰富经验和良好的口碑，代写师资资源比较深厚，对代写质量有保障。
(2)定制化服务
由于作业要求的多样,比如：有些课程作业要求掌握基本的编程语言即可，而有些课程作业要求有一个完善的结构，且可以正常执行相关命令等。这就要求代写机构针对客户的不同需求，制定一份独一无二的编程计划，保证反馈到顾客手中稿件的质量。
(3)专业团队
专业的团队秉着对每一份作业负责的态度，在完成代码的书写后，先尝试执行，如果出现报错等问题，会及时修正，最终给您一份完整的，正确的，高质量的作业，这将为你解决所有的忧虑。
(4)交稿时间
您在寻找代写机构的时候，也需要明确规定交付时间。有些机构没有编程这方面的专业写手，因此不能在规定的时间里面完成您的作业。所以，这就要求您选择一个具备代写能力的机构，它不仅仅要保证提交的稿件质量，也要保证完成稿件的时间。
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数据库代写案例：Database System CSCI235
Task 1 Analysis of relational schemas and normalization
A book is described by a catalog number, a book title, author’s first name, author’s last name, a publisher name, the year the book was published, and a price of the book. An author may write many books and each book may be written by one or more authors. The information is stored in a relational table book as follow:
BOOK (CatalogNum, BookTitle, AuthorFName, AuthorLName, PublisherName,
YearOfPublication, Price)
The following dependencies exist in the relational table BOOK:
· 𝐶𝑎𝑡𝑎𝑙𝑜𝑔𝑁𝑢𝑚 → 𝐵𝑜𝑜𝑘𝑇𝑖𝑡𝑙𝑒, 𝑃𝑢𝑏𝑙𝑖𝑠ℎ𝑒𝑟𝑁𝑎𝑚𝑒, 𝑌𝑒𝑎𝑟𝑂𝑓𝑃𝑢𝑏𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛
· 𝐵𝑜𝑜𝑘𝑇𝑖𝑡𝑙𝑒, 𝑃𝑢𝑏𝑙𝑖𝑠ℎ𝑒𝑟𝑁𝑎𝑚𝑒, 𝑌𝑒𝑎𝑟𝑂𝑓𝑃𝑢𝑏𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 → 𝑃𝑟𝑖𝑐𝑒
· 𝐴𝑢𝑡ℎ𝑜𝑟𝐹𝑖𝑟𝑠𝑡𝑁𝑎𝑚𝑒, 𝐴𝑢𝑡ℎ𝑜𝑟𝐿𝑎𝑠𝑡𝑁𝑎𝑚𝑒, 𝐵𝑜𝑜𝑘𝑇𝑖𝑡𝑙𝑒 → 𝐶𝑎𝑡𝑎𝑙𝑜𝑔𝑁𝑢𝑚
(i) Find all the minimal super key of the relational table BOOK. List the derivations of all minimal keys.
(ii) Identify the highest normal form of the relational table BOOK. List the
justifications for each highest normal form found.
(iii) Decompose the relational table BOOK into minimal number of relational tables in BCNF. List all relational tables obtained from the decompositions.
Task 2 Indexing
Using the relational table LINEITEM of the sample database TPCHR, for each
one of the queries listed below:
i. Find all the discount (l_discount) of all the items that are shipped
(l_shipdate) most recently. Hint. Most recently mean the latest shipment date.
ii. Find the total number of items shipped by air (l_shipmode) in 1998 (l_shipdate).
iii. Find the order number (l_orderkey) and item number (l_linenumber)
that have the highest discount (l_discount).
iv. Find the total number of item per line status (l_linestatus). List the line
status and the total items per line status.
v. Find the order key (l_orderkey), line item number (l_linenumber), line
status (l_linestatus), shipment date (l_shipdate) and shipment mode (l_shipmode) of all orders with the order number (l_orderkey) 1795718, 1799046, and 1794626.
a) Construct an SQL statement that produces the required output specified in the statement.
b) Find the best possible indexing of a relational table LINEITEM. The best possible indexing means that a database system will compute a query with an index proposed by you using the smallest number of read block operations. Note that you can create only one index per query, and there is no need to find
indexes that speed up the processing of more than one query. Use the explain plan and show plan statements to justify your solutions.
