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Null (SQL) (Polish Wikipedia)

Analysis of information sources in references of the Wikipedia article "Null (SQL)" in Polish language version.

refsWebsite
Global rank Polish rank
2sqlservercentral.com
low place
low place
2postgresql.org
low place
8,177th place
2web.archive.org
1st place
1st place
1microsoft.com
153rd place
281st place
1thethirdmanifesto.com
low place
low place
1warwick.ac.uk
4,378th place
5,917th place
1sfdama.org
low place
low place

microsoft.com (Global: 153rd place; Polish: 281st place)

msdn2.microsoft.com

  • Creating Unique Indexes, [w:] MSDN [online], Microsoft, wrzesień 2007 [dostęp 2012-08-27], Cytat: Handling NULL Values
    For indexing purposes, NULL values compare as equal. Therefore, a unique index, or UNIQUE constraint, cannot be created if the key values are NULL in more than one row. Select columns that are defined as NOT NULL when columns for a unique index or unique constraint are chosen. (ang.).

postgresql.org (Global: low place; Polish: 8,177th place)

  • PostgreSQL 8.0.14 Documentation: Index Types [online], PostgreSQL [dostęp 2012-08-27], Cytat: B-trees can handle equality and range queries on data that can be sorted into some ordering. In particular, the PostgreSQL query planner will consider using a B-tree index whenever an indexed column is involved in a comparison using one of these operators: < ≤ = ≥ >
    Constructs equivalent to combinations of these operators, such as BETWEEN and IN, can also be implemented with a B-tree index search. (But note that IS NULL is not equivalent to = and is not indexable.) (ang.).
  • PostgreSQL 8.0.14 Documentation: Unique Indexes [online], PostgreSQL [dostęp 2012-08-27], Cytat: When an index is declared unique, multiple table rows with equal indexed values will not be allowed. Null values are not considered equal. A multicolumn unique index will only reject cases where all of the indexed columns are equal in two rows. (ang.).

sfdama.org (Global: low place; Polish: low place)

sqlservercentral.com (Global: low place; Polish: low place)

  • Michael Coles, Four Rules for Nulls, „SQL Server Central”, Red Gate Software, 27 czerwca 2005 (ang.).
  • Michael Coles, Null Versus Null?, „SQL Server Central”, Red Gate Software, 26 lutego 2007 (ang.).

thethirdmanifesto.com (Global: low place; Polish: low place)

  • Hugh Darwen, Chris Date, The Third Manifesto [online] [dostęp 2012-09-04] (ang.).

warwick.ac.uk (Global: 4,378th place; Polish: 5,917th place)

dcs.warwick.ac.uk

  • Hugh Darwen, The Askew Wall [online] [dostęp 2012-09-04] [zarchiwizowane z adresu 2016-03-13] (ang.).

web.archive.org (Global: 1st place; Polish: 1st place)

  • Hugh Darwen, The Askew Wall [online] [dostęp 2012-09-04] [zarchiwizowane z adresu 2016-03-13] (ang.).
  • Chris Date, Abstract: The Closed World Assumption [online], Data Management Association, San Francisco Bay Area Chapter [dostęp 2007-05-29] [zarchiwizowane z adresu 2007-05-19] (ang.).