er diagram examples

Label:we need to consider the relationship between the data when we set up the database, in order to clarify the relationship between the data we need to do a uniform collation of the data. For the more complex database, we need to establish a database model, which can be divided into two steps: first, the structure analysis of the database and the use of tree, table and other descriptive data, and then analyze the database operation methods, rules and additions and deletions of the database ope

is also an example to illustrate what happened we think the two entities are connected.When we mention the relationship between entities, the first thing I'm afraid of is the one to One,one to many and many tomany the three types of contact, these contact types are most familiar to you. I am not proficient in the original concept of ER diagram, but in CDM, there are three other properties that can be set:

Label:er diagram The E-r graph, also known as the entity-contact graph (Entities Relationship Diagram), provides methods for representing entity types, attributes, and connections to describe the conceptual model of the real world. Entity is to see the touch or can be perceived acceptance of the objective existence, the attribute is used to describe the entity, contact nature is the relationship between ent

In the painting ER diagram when looking for a more useful and professional point of the tool, looking for a half-day finally chose the seemingly less professional EA to draw ER diagram Briefly explain how the EA is implemented to draw ER graphs First, the Operation proc

Label:Today, Azusa brother asked me to first design a database table for the project, it is best to draw an ER diagram out. Er diagram I know what, because before the database and application of the water class,, but now forget almost, asked the degree Niang, what is the ER

1. E-r graph is also called entity-Contact diagram (entities relationship Diagram), which provides methods for representing entity types, attributes, and connections to describe the conceptual model of the real world. It is an effective method to describe the conceptual structure model of the real world. is a way of representing the conceptual model, the entity type is represented by a rectangle, the entity

redundancy, update exception, insert exception, delete exception)3NF: The non-primary attribute is directly dependent on the candidate key. (non-conforming data redundancy, update exception, insert exception, delete exception)BCNF: A non-primary property directly depends entirely on the candidate key, and the primary attribute is directly full function dependent on the key that does not contain it.The database design can be divided into three steps:1. Drawing E-r2. Convert the E-r

To draw an ER diagram with Visio The 3 elements of an ER diagram are entities, attributes, and relationships. When we learn the base of the database, the general ER diagram looks like this: A square is an entity, a circle is

database. Through the menu bar "Databas" e--> "Connect to Database", enter the corresponding hostname, port, username, password, and connect successfully;After the successful connection, you can see the monitoring information, as well as the database tables;2.2 Through the menu bar "Database", select "Reverse Engineer ...", enter the connection information, and all the way next, finally Excute and close.You can see that in the Err diagram area more t

Tags: c style blog A HTTP extin the design of the database, think of the exact installation EA software, see if I can use it. EA painting ER model. The results show that not only can draw, but also the entire database design (Generate SQL script). below to the computer room toll system users -- students as an example. Students can view the balance, can view the computer record, can view the status of the computer, can view the recharge record, can ch

1. Find the Entity (rectangle), attribute (ellipse), relationship (Diamond) relationship in the condition into 1:1,1:n,m:n, list er diagram2.Conversion method of -1:1 Contact-Two entities are transformed into a relational schema, which is the original attribute-The relationship can be merged with any entity, the attributes of the relationship, and the main code of the other entity to be added to the merged relational patternTransformation method of -1

database--the method of transforming from ER diagram to relational mapping Specific steps: 1.For each strong entity type E. Create a new table. Include as its columns, all the simple attributes and easy components of the composite attributes of E. Identify the PRI Mary Key and the alternate keys. Do not include any multi-valued attribute as a key. If The unique field of an entity is a multi-valued attribut

%.] Sys.columns Cjoin [%catalog%.] Sys.objects o on (o.object_id = c.object_id)join [%catalog%.] Sys.schemas u on (u.schema_id = o.schema_id)join [%catalog%.] Sys.types T on (t.user_type_id = c.system_type_id)Left outer join[%catalog%.] Sys.identity_columns i on (i.object_id = c.object_id andi.column_id = c.column_id)Left outer join[%catalog%.] Sys.default_constraints D on (d.object_id = c.default_object_id)whereO.type in (' U ', ' S ', ' V ')[and U.name =%.q:owner%][and O.name=%.q:table%]ORDER

Images cannot be copied directly. You can fill it up later. 1. Open PowerDesigner, select File | Reverse Engineer | Database ..... in the new Physical Data Model dialog box, select the type of database you want to connect to, and click OK. 2. In the Database Reverse Engineering window, select the Using a data source option. Click the database icon at the far right of the next line to eject the connect to a Data source window. Select the first item: ODBC machine data source. Click t

digits ( case when a.isnullable=1Then'√'ELSE"'END) allow null, ISNULL (E.text,"') Default value, ISNULL (G.[value],"'As field description from syscolumns a left JOIN systypes b on A.xtype=b.xusertype INNER JOIN sysobjects D on a.id=D.id and D.xtype='U'and D.name'dtproperties'Left JOIN syscomments e on A.cdefault=E.id left JOIN sys.extended_properties g on a.ID=g.major_id and A.colid=g.major_id ORDER by a.id, A.colorder Next, export the data dictionary: First, click Export in the top right co

the direction of the link, generally with a verb or a dynamic table.For example, the "Students to subject" group box should be filled in with "owning", and "belong" in the "Lessons to student" group box. (Here is just an example, maybe some words are not very reasonable).Vii. Mandatory definition of linkagesMandatory the mandatory relationship between the form and this direction. Select this check box to create a vertical line of contact lines on the contact line. Not selecting this check box i

1. Enter Tools-->execute commands-->edit/run script, execute the following scripts to achieve all the fields to capitalize;Option ExplicitValidationmode = TrueInteractivemode = Im_batchDim MDL ' current model' Get current modelSet mdl = ActivemodelIf (MDL is Nothing) thenMsgBox "Not open a model"ElseIf not MDL. IsKindOf (Pdpdm.cls_model) ThenMsgBox "The current model is not a PDM"Else' Call handlerProcessFolder MDLEnd If' handler calledPrivate Sub ProcessFolder (folder)Dim Tab ' table to be proc

Visio 2010 Reverse-Engineering The MySQL database build ER Database model diagram1, first need to download from MySQL for database link drive ODBCYes: http://dev.mysql.com/downloads/connector/odbc/Download it according to the appropriate version and install it locally after downloading2, start Visio2010 (other version of self-study)When creating a new document, select "Software and Database" in the template category, asThen jump to "select template",

examples: http://www.hightopo.com/demos/index.htmlObviously http://www.hightopo.com/demos/index.html compared to the http://www.hightopo.com/guide/readme.html page, for HT old users including our own to do technical support, All feel more intuitive to find examples, but for the HT beginner, facing this heap of hundreds of generic components, network topology diagram