Relational data keys

Generic function, with the only given method fetching candidate key lists for relation schemas.

Usage

keys(x, ...)

keys(x, ...) <- value

Arguments

x

a relational schema object, such as a relation_schema or database_schema object, or a relational data object, such as a relation or database object.

...

further arguments passed on to methods.

value

A list of lists of character vectors, of the same length as keys(x, ...). The number of keys for an element of x can be changed.

Value

A list containing lists of unique character vectors, representing candidate keys for each element of x.