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Questions tagged [cardinality]

In data modeling, the cardinality of one data table with respect to another data table is a critical aspect of database design. Relationships between data tables define cardinality when explaining how each table links to another. In the relational model, tables can be related as any of: many-to-many, many-to-one (rev. one-to-many), or one-to-one. This is said to be the cardinality of a given table in relation to another.

In data modeling, the cardinality of one data table with respect to another data table is a critical aspect of database design. Relationships between data tables define cardinality when explaining how each table links to another.

In the relational model, tables can be related as any of: many-to-many, many-to-one (rev. one-to-many), or one-to-one. This is said to be the cardinality of a given table in relation to another.

Wikipedia article

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Does Cardinality happen one at a time or it is about the whole life of the data?

A laboratory has several chemists who work on one or more projects. While working on these projects a chemist may use different laboratory equipment. The laboratory needs to know the following information…
Allen
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How do I finish this recursive statement?

def search_sequence( seq, item ): """ Search a sequence for the given item. PROVIDE AN IMPLEMENTATION (TASK #2). This function should use **car** and **cdr**. :param seq: the sequence to be searched. :param item: the item to be…
aceofspades
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In one to many relationship does there exist element from first table that are not connected to element from second table

when we have two tables, suppose A and B,there exists one to many relationship between these two, than can there be element from A that are not connected to any element from B?
dato nefaridze
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Find the Cardinality of Natural Join

|X| represents number of tuples in X bold letters represent keys in the relation Consider the relations R(A, B) and S(A, C), and that R has a foreign key on A that references S. |R ✶ S| (where ' * ' represents natural join) is: The options are:…
rdr2
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