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Number of relationship models

2022-07-04 10:13:00 【Wildcraner】

Calculation formula ： Number of relational patterns = Number of entity sets + The number of many to many connections

Example 1
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As in this question , The number of entity sets is 3 individual , Many to many numbers are 2 individual , Then the number of relational patterns =5

Example 2
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As in this question , The number of entity sets is 3 individual , Many to many numbers are 1 individual , Then the number of relational patterns =4

Example 3
Insert picture description here As in this question , The number of entity sets is 4 individual , Many to many numbers are 2+1+2 individual , Then the number of relational patterns =9

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