Powerdesigner Conceptual Model Description

Powerdesigner Conceptual Model Description

Environment

Powerdesigner 12.5

Windows XP Chinese Version

I. Importance of conceptual models

Powerdeigner is the most powerful and excellent data modeling tool and is the greatest product of Sybase. At present, the latest version is 12.5, which has been used since 9, and the understanding of PD is gradually deepened.

Usually at work, we can see that PD is used to create several tables. In fact, it is used for PDM. In this case, we can do it as soon as we come up. In fact, using PD, it is an insult to powerful PD. Is PD just playing like this?

What are the steps for database design? Could you just give it a PDM?

Below is a brief review of the basic steps of database design described in university textbooks:
1. Requirement Analysis
Find some conceptual terms from the system requirements, select them, and understand the relevant attributes of these terms. This part is manual and PD cannot do anything.
2. Conceptual Structure Design
Focusing on the selection of nouns, find out the relationship (independent, one-to-one, one-to-many, many-to-many, inherited five relations), and use the E-R diagram to describe, this is the practice of university textbooks. In PD, this process can be described by CDM (concept model). in PDM, the entity conceptual model representation is clearer and better than E-R.
3. Logical Structure Design
In fact, it is to design the structure of the table and the main and External Relations Between the tables. This part corresponds to PDM (Physical Model) in PD, and physical models in PD are generally directly generated from the conceptual model. That is to say, the physical model can be automatically generated as long as you make a good conceptual model.
Of course, some adjustments and optimizations are generally required to generate such results.
4. Physical Structure Design
With PDM, the physical design of the database is easy to use, and the database creation scripts of various database systems can be exported directly from PDM.
5. database establishment and Testing
This process is also very simple. You can see the execution of the database creation script. It is unreasonable to re-Modify the PDM and generate an SQL statement.
6. database operation and maintenance.
This is generally a DBA thing, such as a long time, a large amount of data, adding indexes to some columns, tuning, and so on.

From this we can see that it is unreasonable to build PDM as soon as it comes up. In fact, a thorough understanding of the conceptual model is required for PDM. This kind of understanding can be avoided, but at least there is a picture in mind.

The advantage of building a CDM conceptual model is that it is easy to communicate and is universal throughout the world. Can you use the foreign key relationship of PDM to view the data relationship? If there are multiple foreign keys in a table and the foreign key Association is like spider's, It will be dizzy. No one can understand it!

2. Use PD to create a database conceptual model

1. One-to-one CDM

Describes an extension information corresponding to a system user. The extended information depends on the existence of user information. In addition, one extension information can only have one user information.

Link settings:

Generate PDM

2. One-to-multiple CDM

CDM describes a model in which a company has multiple managers. Of course, a company can have no managers (the boss is the head of the light pole ). But a manager must belong to a company.

Link settings:

Generated PDM

3. many-to-many CDM

The following describes the relationship between an actor and a role. An actor can assume multiple roles, and a role can be played by different actors, such as Lin, sister of A Dream of Red Mansions, when I was a child, I got an actor a to show it. When I grew up, I got an image from actor B.

Link settings, many-to-many relationships are the easiest, and generally do not need to be set:

The generated PDM is as follows:

4. inheritance relationship CDM

It describes an inheritance relationship. For example, there is an educational administration system where the user divides the student teacher into different information filled by the teacher and the student at registration, but there is public information.

Link Configuration. If you don't need it, you can integrate the link without configuring it.

The generated PDM is as follows:

Maybe you will find that there are only four of the five tables. Haha, a single table is independent of anyone. Do you still use painting?

Iii. Summary

1. database modeling is the most important step in system design. the conceptual model can well describe the relationship between data and accurately generate a physical model conforming to a certain standard paradigm from the conceptual model.

2. CDM can describe more subtle data relationships, such as 0-n and 1-N, which directly affects data service constraints, but cannot be described using PDM. CDM saves communication costs for business communication.

3. CDM also provides a basis for later understanding the underlying business data relationship, especially in many tables. If there is no CDM, only the person who designs the database knows the underlying relationship.

4. If there are many tables and modules, we can also talk about CDM subcontracting for management. This will avoid reading troubles caused by drawing all entity relationships in one graph.

5. PD also has many other powerful functions, such as database response to PDM, PDM export script, and PDM export Java model object and XML model. You can also generate persistence code at the DaO layer, even HBM files, business process modeling, and data dictionary reports. But what PD is best at is CDM --> PDM --> SQL, database reverse engineering, and report functions.

Powerdesigner Conceptual Model Description