Talk:Cardinality (SQL statements)

Cardinality in math

Shouldn't this article point to Cardinality, somehow?
--Jerome Potts (talk) 05:30, 11 January 2008 (UTC)[reply]

SQL

Cardinality is not peculiar to SQL. GregorB (talk) 20:02, 30 January 2008 (UTC)[reply]

Input from DerekAsirvadem

I removed the following paragraphs from the 05:42, 29 January 2009 version of the article, as the notes are more appropriate on the discussion page. The notes were added by DerekAsirvadem. Currently, I don't have an opinion about the notes. But let's discuss them.

1 There is no such thing as "normal" cardinality. In order for such a concept to exist, there must be some pre-existing measure (there is not). Cardinality is a relative term, relative to the object: if the table has a million rows, and there are close to a milliion values, the column has high cardinality; if the values are few, the column has low cardinality. There is no measure outside the table against which "normal" can be determined.

2 The highest level of cardinality is uniqueness: one unique value per row. That may well be a range of more than one million values.

3 The definiions are adequate but the examples are poor. Troels Arvin (talk) 09:17, 29 January 2009 (UTC)[reply]