{"id":510,"date":"2026-06-10T03:58:42","date_gmt":"2026-06-10T03:58:42","guid":{"rendered":"https:\/\/mitalgoswami.in\/?p=510"},"modified":"2026-06-17T03:11:48","modified_gmt":"2026-06-17T03:11:48","slug":"dr-e-f-codd-rules","status":"publish","type":"post","link":"https:\/\/mitalgoswami.in\/?p=510","title":{"rendered":"Dr.E.F.Codd Rules"},"content":{"rendered":"\n

Dr. E. F. Codd’s 12 Rules of Relational Database Management Systems (RDBMS)<\/strong><\/p>\n\n\n\n

Dr. Edgar F. Codd proposed these rules to define what a true Relational Database Management System should be.<\/p>\n\n\n\n

Rule 0: Foundation Rule<\/h3>\n\n\n\n

A system must use its relational capabilities exclusively to manage the database.<\/p>\n\n\n\n

Rule 1: Information Rule<\/h3>\n\n\n\n

All information in the database must be represented only as values in tables (rows and columns).<\/p>\n\n\n\n

Rule 2: Guaranteed Access Rule<\/h3>\n\n\n\n

Every data value must be accessible by specifying:<\/p>\n\n\n\n

    \n
  • Table name<\/li>\n\n\n\n
  • Primary key (row identifier)<\/li>\n\n\n\n
  • Column name<\/li>\n<\/ul>\n\n\n\n

    Rule 3: Systematic Treatment of NULL Values<\/h3>\n\n\n\n

    NULL values must be supported and treated systematically to represent missing or unknown information.<\/p>\n\n\n\n

    Rule 4: Dynamic Online Catalog Rule<\/h3>\n\n\n\n

    The database dictionary (metadata) must be stored as relational tables and be accessible using the same query language.<\/p>\n\n\n\n

    Rule 5: Comprehensive Data Sublanguage Rule<\/h3>\n\n\n\n

    The system must support at least one relational language that can:<\/p>\n\n\n\n

      \n
    • Define data<\/li>\n\n\n\n
    • Manipulate data<\/li>\n\n\n\n
    • Define views<\/li>\n\n\n\n
    • Specify integrity constraints<\/li>\n\n\n\n
    • Manage transactions<\/li>\n<\/ul>\n\n\n\n

      (SQL is the most common example.)<\/p>\n\n\n\n

      Rule 6: View Updating Rule<\/h3>\n\n\n\n

      All theoretically updatable views should be updatable by the system.<\/p>\n\n\n\n

      Rule 7: High-Level Insert, Update, and Delete Rule<\/h3>\n\n\n\n

      The system must support set-level operations for INSERT, UPDATE, and DELETE, not just record-by-record processing.<\/p>\n\n\n\n

      Rule 8: Physical Data Independence<\/h3>\n\n\n\n

      Changes in physical storage methods should not affect application programs.<\/p>\n\n\n\n

      Rule 9: Logical Data Independence<\/h3>\n\n\n\n

      Changes in logical structure (such as adding columns) should not require changes in application programs.<\/p>\n\n\n\n

      Rule 10: Integrity Independence<\/h3>\n\n\n\n

      Integrity constraints should be definable in the database and independent of application programs.<\/p>\n\n\n\n

      Rule 11: Distribution Independence<\/h3>\n\n\n\n

      Users should not need to know whether data is distributed across multiple locations.<\/p>\n\n\n\n

      Rule 12: Non-Subversion Rule<\/h3>\n\n\n\n

      If a low-level language is provided, it must not bypass integrity rules and constraints defined in the relational system.<\/p>\n\n\n\n

      Summary Table<\/h2>\n\n\n\n
      Rule No.<\/th>Rule Name<\/th><\/tr><\/thead>
      0<\/td>Foundation Rule<\/td><\/tr>
      1<\/td>Information Rule<\/td><\/tr>
      2<\/td>Guaranteed Access Rule<\/td><\/tr>
      3<\/td>NULL Values Rule<\/td><\/tr>
      4<\/td>Dynamic Online Catalog<\/td><\/tr>
      5<\/td>Comprehensive Data Sublanguage<\/td><\/tr>
      6<\/td>View Updating Rule<\/td><\/tr>
      7<\/td>High-Level Insert, Update, Delete<\/td><\/tr>
      8<\/td>Physical Data Independence<\/td><\/tr>
      9<\/td>Logical Data Independence<\/td><\/tr>
      10<\/td>Integrity Independence<\/td><\/tr>
      11<\/td>Distribution Independence<\/td><\/tr>
      12<\/td>Non-Subversion Rule<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

      Exam Tip:<\/strong> Many universities refer to these as Codd’s 12 Rules<\/strong>, but there are actually 13 rules numbered 0 through 12<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"

      Dr. E. F. Codd’s 12 Rules of Relational Database Management Systems (RDBMS) Dr. Edgar F. Codd proposed these rules to define what a true Relational Database Management System should be. Rule 0: Foundation Rule A system must use its relational capabilities exclusively to manage the database. Rule 1: Information Rule All information in the database […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[30],"tags":[],"class_list":["post-510","post","type-post","status-publish","format-standard","hentry","category-oracle"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=\/wp\/v2\/posts\/510","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=510"}],"version-history":[{"count":1,"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=\/wp\/v2\/posts\/510\/revisions"}],"predecessor-version":[{"id":511,"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=\/wp\/v2\/posts\/510\/revisions\/511"}],"wp:attachment":[{"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=510"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=510"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mitalgoswami.in\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=510"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}