When you design a new functional module, the server will ask you specific shoes have what kinds of relationship between the entity and, if you did not think clearly or describe vague, then it is necessary to learn about ER diagrams.
Have you encountered similar problems?
- Coupon design module, there are several confusing concepts. For example, operators of the new batch of coupons, which the user then picking up a coupon, which is likely to be a multi-use (such as uber). I ask what are these three is the relationship between, and how to distinguish among these three ......
- Product Design module, spu, sku, merchandise can easily be confused, there is one step further product bar code, product code, and so on. How and services to end children's shoes to explain them is a very difficult thing.
- A little more complicated, if the design mall system, the server will ask you this mall shoes of how to build the core of what things.
How to solve these problems?
In fact, these seemingly complex problem, as the PM first with ER diagrams to sort out clearly, and then confirm that the server is the most appropriate way of working. You know the text is difficult to describe clearly. The prototype wireframes can not express them directly.
What ER diagram is?
Let me talk about the concept, ER diagram is used to describe the entity relationship model in the real world, the so-called entity is present and can be distinguished objectively or logically anyone or anything.
ER diagram What is the role?
The core elements of ER diagrams will lead you to the most appropriate way to achieve understanding of technology to standardize the description of the function module, in fact, the physical structure of the database. And this description is unambiguous, the clearest PM convey design ideas.
Coupons ER diagram
Take the above case 1 to draw an ER diagram, statements like this is very clear, which links the "Generate" attribute can not draw.
Of course, if the traffic is not the same, such as defined under each line receive the coupons and used only once, like shopping malls. That figure should be so, note the difference.
ER diagram which contains several elements?
entity
It refers to something objectively or logically distinguishable from each other.
FIG represented by a rectangle in the ER, the entity name indicate the rectangle.
Attributes
Entity having a certain characteristic, an entity may be a plurality of attributes to describe.
In FIG ER by ovals, and the connected undirected edges with the corresponding entity.
contact
Also known as relationship, reflecting the association between internal entity or entities. Internal contact entity generally refers to links between the various attributes of the entity; the links between entities generally refers to a set of links between the different entities.
In FIG ER by diamonds represent, contact name stated diamond frame, and are connected together by directed edges with no relevant entities, while in the type (a non-contact on the side next to the superscript: 1,1: n or m: n ).
Cable
Between entities and attributes; and the link between the entities; Contact between the properties are connected with a straight line, and marked types of links in a straight line.
ER diagram how to draw?
How to express elements
Paint step
- This module first determine which of several core subject and what specific features,
- Secondly, think about the relationship between these objects, how to change each other.
- Finally, the method they use ER diagrams express.
- Of course, need to try to streamline and optimize physical properties.
Then the beginning of the two cases also painted look, easy understanding.
B2C mall merchandise module
B2C mall system
Note that there are concepts of a warehouse.
to sum up
ER diagram is an efficient means to convey the functions of the state machine also. After do not think that there is no way to make the product do not learn, but learn these methods for the design and implementation level of efficiency will be greatly improved.
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