作者: negotiable 時(shí)間: 2025-3-21 22:31 作者: chastise 時(shí)間: 2025-3-22 02:38
Fatih Yilmaz,Yunus Emre Yuksel,Murat Ozturkhey understand the problem completely. There are two things we need to do: understand what tasks all the people who will use the system need to carry out and then figure out what data we will need to store to support them. Use cases and class diagrams as shown in Figure 3-1 are a great way to start to consolidate our understanding of a problem作者: chlorosis 時(shí)間: 2025-3-22 04:33 作者: 好色 時(shí)間: 2025-3-22 09:28
Eldan Cohen,J. Christopher Beck and complexities about the real-world problem. We then looked at a number of situations that occur in many models in the hope that these would be useful when difficult situations arose in other contexts作者: Oligarchy 時(shí)間: 2025-3-22 16:30 作者: angiography 時(shí)間: 2025-3-22 17:57 作者: 油氈 時(shí)間: 2025-3-22 21:12 作者: 核心 時(shí)間: 2025-3-23 02:33
Developing a Data Model,t deal can be learned about a problem by questioning some of the details of simple relationships, particularly the number of objects involved at each end of a relationship. In this chapter, you’ll be introduced to a few problems that frequently occur in order to enlarge your armory for attacking tricky situations作者: FORGO 時(shí)間: 2025-3-23 07:57 作者: 好色 時(shí)間: 2025-3-23 12:20
More on Keys and Constraints,bles. In this chapter, we take another look at some of these ideas and think about some alternative possibilities. In particular, we take a closer look at primary keys and how to choose them. We also take a look at how we can maintain referential integrity when data is being constantly updated作者: 用肘 時(shí)間: 2025-3-23 15:19
Other Implementations,e as a set of normalized tables related by foreign keys. The previous two chapters showed how we could efficiently enter data into these tables and use queries to extract meaningful information and reports作者: 正論 時(shí)間: 2025-3-23 20:12 作者: Anticoagulants 時(shí)間: 2025-3-23 23:51 作者: 祝賀 時(shí)間: 2025-3-24 05:00 作者: 媽媽不開心 時(shí)間: 2025-3-24 06:39
Waldemar Cruz,Fanghui Liu,Laurent Micheled with two separate classes, for example Lecturers and Students, and then begin to realize that there is a great deal of information in common or that they are involved in the same relationships (who has parking permits, say). How do we handle these “same only different” cases in a pragmatic way?作者: 羽毛長(zhǎng)成 時(shí)間: 2025-3-24 13:55 作者: 珠寶 時(shí)間: 2025-3-24 17:03
What Can Go Wrong,sarily the correct one. Often a table or spreadsheet is designed to mimic a possible data entry screen or a hoped-for report. This practice may be adequate for solving the immediate problem (e.g., storing the data somewhere); however, mimicking a data entry screen or report in your database design o作者: CAPE 時(shí)間: 2025-3-24 20:19 作者: 沙文主義 時(shí)間: 2025-3-25 02:58
Learning from the Data Model,first attempt at determining the data that is necessary to support those tasks and formed an initial data model, which we depicted with a class diagram. In this chapter, we look more closely at the data model to see how it can further our understanding of a database system作者: 相反放置 時(shí)間: 2025-3-25 03:40
Developing a Data Model,ry out. Tasks were represented with use cases, and a simple data model was developed to represent the required data. In Chapter 4, you saw that a great deal can be learned about a problem by questioning some of the details of simple relationships, particularly the number of objects involved at each 作者: NICHE 時(shí)間: 2025-3-25 11:07
Generalization and Specialization,might like. We might find that we have some objects for which some of the attributes do not really apply. For example, if we have a class to record information about all the people associated with a company, we might find that some have hourly pay rates while others have annual salaries. In many res作者: stroke 時(shí)間: 2025-3-25 14:34 作者: enterprise 時(shí)間: 2025-3-25 17:54
More on Keys and Constraints, relationships between classes with primary and foreign keys and then applied the ideas of normalization to ensure the attributes were in the right tables. In this chapter, we take another look at some of these ideas and think about some alternative possibilities. In particular, we take a closer loo作者: vibrant 時(shí)間: 2025-3-25 22:38 作者: CAND 時(shí)間: 2025-3-26 03:12
User Interface,. We specified these requirements in terms of use cases, and most fell into one of two categories: tasks a user would need to carry out to enter data efficiently and tasks for retrieving information in the form of different reports作者: 向下五度才偏 時(shí)間: 2025-3-26 05:31 作者: 清澈 時(shí)間: 2025-3-26 10:36
Karittha Im-orb,Amornchai ArpornwichanopThe decision to set up a small database usually arises because there is some specific task in mind: a scientist may have some experimental results that need safekeeping; a small business may wish to produce invoices and monthly statements for its customers; a sports club may want to keep track of teams and subscriptions作者: monochromatic 時(shí)間: 2025-3-26 13:12 作者: JAUNT 時(shí)間: 2025-3-26 17:56 作者: 無聊的人 時(shí)間: 2025-3-26 23:57
Normalization,We are doing pretty well at designing a database. So far, you have learned how use cases and a data model can help you understand many of the complexities of the actual problem you are trying to represent. In the previous chapter, you saw how to represent the main parts of the data model in a relational database. To recap:作者: 惰性氣體 時(shí)間: 2025-3-27 04:16 作者: 商業(yè)上 時(shí)間: 2025-3-27 07:37 作者: epicardium 時(shí)間: 2025-3-27 12:12 作者: Intersect 時(shí)間: 2025-3-27 15:47
Yi Ding,Yonghua Song,Changzheng Shaosarily the correct one. Often a table or spreadsheet is designed to mimic a possible data entry screen or a hoped-for report. This practice may be adequate for solving the immediate problem (e.g., storing the data somewhere); however, mimicking a data entry screen or report in your database design o作者: Accommodation 時(shí)間: 2025-3-27 17:51
Fatih Yilmaz,Yunus Emre Yuksel,Murat Ozturko make sure we really understand the problem. This may sound obvious, but it is surprising how often people set about implementing a database before they understand the problem completely. There are two things we need to do: understand what tasks all the people who will use the system need to carry 作者: Canary 時(shí)間: 2025-3-28 00:07 作者: fetter 時(shí)間: 2025-3-28 04:51
https://doi.org/10.1007/978-3-8349-3958-6ry out. Tasks were represented with use cases, and a simple data model was developed to represent the required data. In Chapter 4, you saw that a great deal can be learned about a problem by questioning some of the details of simple relationships, particularly the number of objects involved at each 作者: 積云 時(shí)間: 2025-3-28 07:35
Waldemar Cruz,Fanghui Liu,Laurent Michelmight like. We might find that we have some objects for which some of the attributes do not really apply. For example, if we have a class to record information about all the people associated with a company, we might find that some have hourly pay rates while others have annual salaries. In many res作者: glans-penis 時(shí)間: 2025-3-28 13:24
Eldan Cohen,J. Christopher Beckloped an initial data model. By looking carefully at the details of the model, we were able to develop questions to help understand further subtleties and complexities about the real-world problem. We then looked at a number of situations that occur in many models in the hope that these would be use作者: tangle 時(shí)間: 2025-3-28 15:13 作者: Ophthalmologist 時(shí)間: 2025-3-28 21:18
,Single Constant Multiplication for?SAT, this chapter, we are going to look at how to get information back out again. The data will be stored in many separate tables, and depending on the questions we are asking, we will need to combine data from those tables in a number of different ways. This chapter is just an introduction to the art o作者: NADIR 時(shí)間: 2025-3-29 00:05 作者: B-cell 時(shí)間: 2025-3-29 03:12 作者: 流動(dòng)性 時(shí)間: 2025-3-29 08:09 作者: Accolade 時(shí)間: 2025-3-29 13:24 作者: 自傳 時(shí)間: 2025-3-29 15:33
Guillaume Escamocher,Barry O’Sullivan. We specified these requirements in terms of use cases, and most fell into one of two categories: tasks a user would need to carry out to enter data efficiently and tasks for retrieving information in the form of different reports作者: MOAN 時(shí)間: 2025-3-29 20:52
Clare ChurcherTaps into the same audience as Database design for Mere Mortals.Is shorter and more readable than the competing book.Uses the latest methods (use-case driven) and diagramming notation (the UML)作者: AMITY 時(shí)間: 2025-3-30 03:53
