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I am new to database and I saw some database diagram with

  • has[1:0-N],
  • is[1:0-N],
  • has from[1:1],
  • has to[1:1]

labeled next to the linkages between the "boxes". Where can I find out more on what each of the above means?

For a database diagram to have the above "labels", what is the diagram called?

Craig Walker
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Lopper
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3 Answers3

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You might be talking about an Entity Relationship Model.

http://en.wikipedia.org/wiki/Entity-relationship_model

As far as the relationships you're talking about, those should be representing how different tables relate to each other, such as:

Table A is Table B
Table A has N references to Table B
Table A has a foreign key to/from Table B

chustar
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These are basically the relationships in RDBMS(databases) and 1:0-N means 1 value of an attribute of one table has many relations with many values of another table attribute's value.

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These labels refer to Cardinality, which describes the number of rows in one table that another row in another table is related to.

Craig Walker
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