erd | 易学教程

Anyone have an ERD symbols quick reference?

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问题 I'm looking for a one-page quick-reference or cheatsheet (preferably in PDF) to the meanings of the various ERD symbols in Crowsfoot/Martin notation. I've done a lot of googling, but have not found a good, concise quick-reference guide, though I'm sure one must exist. 回答1: I've also been looking for a single-page "quick reference" PDF for ERD relationship symbols (i.e. "Crows Feet"). I haven't found anything I've liked, so I created this. I've posted the Full Page, Printable PDF on my blog.

How can I make a schedule table for instructor from tables created

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问题 Problem I need to make scheduale for instructor in training center. I created tables but relation I cannot do. What relation do I make between instructor_course table class table and section table? (Must I have a foreign key from table class and table section? Must I add ClassID FK from table class And SectionID from table section to table Inst_Courses Table?) Table details I need to show schedule for instructor courses within week from Sunday to Thursday. E.g. In Sunday from 2 - 4 clock

Difference between ER diagram and EER diagram

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What is the difference between ERD (Entity relationship diagram) and EERD (enhanced entity relationship diagram)? Martin Thoma Entity-Relationship model You have relationships ( image source ) and attributes ( image source ) that can also be primary keys ( image source ) Enhanced entity–relationship model You have the same as with the ER model plus specialisation partitioning (which are multiple specialisations) generalisation aggregation keys are annotated differently: I would add that ER model is basic model which has all you need for relational algebra as it is (including ISA hierarchy -

How to get ERD diagram for an existing database?

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I have a PostgreSQL database. I want to get its ERD. How can I do so? rudi-moore We used DBVisualizer for that. Description: The references graph is a great feature as it automatically renders all primary/foreign key mappings (also called referential integrity constraints) in a graph style. The table nodes and relations are layed out automatically, with a number of layout modes available. The resulting graph is unique as it displays all information in an optimal and readable layout. from its site krishnakumarp You can use dbeaver to do this. It allows you to export the ER diagram as png/svg

What are the basic rules for defining entities, attributes, and relationships in an ER-Diagram?

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问题 My question is: In order to exist which of the following needs obligatory to have key and attribute? entity entity-type relationship-types relations (tuple with relationship-types) I know my question is a little bit odd, but I am not quite sure what are the rules by building an ER-Diagram. In other words what should mandatory be present in my diagram and what not (e.g Attributes). Thanks in advance. 回答1: In the original Entity-Relationship method, we identfy entity types and relationship

How can I make a schedule table for instructor from tables created

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Problem I need to make scheduale for instructor in training center. I created tables but relation I cannot do. What relation do I make between instructor_course table class table and section table? (Must I have a foreign key from table class and table section? Must I add ClassID FK from table class And SectionID from table section to table Inst_Courses Table?) Table details I need to show schedule for instructor courses within week from Sunday to Thursday. E.g. In Sunday from 2 - 4 clock Instructor Michel give C# Course in ClassRoom A Section B So I created following tables : Courses (like c#

What are the basic rules for defining entities, attributes, and relationships in an ER-Diagram?

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My question is: In order to exist which of the following needs obligatory to have key and attribute? entity entity-type relationship-types relations (tuple with relationship-types) I know my question is a little bit odd, but I am not quite sure what are the rules by building an ER-Diagram. In other words what should mandatory be present in my diagram and what not (e.g Attributes). Thanks in advance. In the original Entity-Relationship method, we identfy entity types and relationship/association types and their relevant attributes. When drawing an ER diagram we pick one or more groups of

How to handle an “OR” relationship in an ERD (table) design?

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问题 I'm designing a small database for a personal project, and one of the tables, call it table C , needs to have a foreign key to one of two tables, call them A and B , differing by entry. What's the best way to implement this? Ideas so far: Create the table with two nullable foreign key fields connecting to the two tables. Possibly with a trigger to reject inserts and updates that would result 0 or 2 of them being null. Two separate tables with identical data This breaks the rule about

Create ERD Of MS CRM Database

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问题 Is there any way to auto create ERD of any existing CRM applicaton. I have MS CRM 11 On Premise and want to take a short look on entities and their relationship diagram. Do we need to create it manually by digging one by one entity and their relationship or is there any other way or any tool do it ? OR This is not a valid question at all ? Ideas will be appreciated if any. Thanks in advance. 回答1: You should check out this article on MSDN. The section at the bottom titled Generate Entity

How to export/save ERD as PDF or as image in phpMyAdmin?

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I have generated an ERD using the Designer in phpMyAdmin. How do I save it as PDF or image? On possible duplicate: The "original" thread is referenced in the answer. This post is intended to be a visual tutorial thread with screenshots which the other thread does not have. silver To save as PDF: 1) Select databse. 2) More > Designer 3) Import/Export coordinates for relational schema 4) Operations (scroll down) > Edit or export relational schema Click Go. 5) Choose your preferences. Click Go. Save the file. To save as image: You can choose "SVG" in Step 5 instead of "PDF", but the it did not