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A tutorial on the first 3 normal forms by Fred Coulson; Description of the database normalization basics by Microsoft; Normalization in DBMS by Chaitanya (beginnersbook.com) A Step-by-Step Guide to Database Normalization; ETNF – Essential tuple normal form Archived March 6, 2016, at the Wayback Machine
The third normal form (3NF) is a normal form used in database normalization. 3NF was originally defined by E. F. Codd in 1971. [2]Codd's definition states that a table is in 3NF if and only if both of the following conditions hold:
Denormalization is a strategy used on a previously-normalized database to increase performance. In computing, denormalization is the process of trying to improve the read performance of a database, at the expense of losing some write performance, by adding redundant copies of data or by grouping data.
Mimer SQL is a DBMS that only implements optimistic concurrency control. [10] Google App Engine data store uses OCC. [11] The Apache Solr search engine supports OCC via the _version_ field. [12] The Elasticsearch search engine updates its documents via OCC. Each version of a document is assigned a sequence number, and newer versions receive ...
It also opens the door to further normalization, which eliminates redundancy and anomalies. Most relational database management systems do not support nested records, so tables are in first normal form by default. In particular, SQL does not have any facilities for creating or exploiting nested tables. Normalization to first normal form would ...
Modifications at the logical level are necessary whenever the logical structure of the database is altered (for example, when money-market accounts are added to banking system). Logical Data independence means if we add some new columns or remove some columns from table then the user view and programs should not change.
Some - can only reverse engineer the entire database at once and drops any user modifications to the diagram (can't "refresh" the diagram to match the database) Forward engineering - the ability to update the database schema with changes made to its entities and relationships via the ER diagram visual designer
Interfaces for interactive data transformation incorporate visualizations to show the user patterns and anomalies in the data so they can identify erroneous or outlying values. [ 9 ] Once they've finished transforming the data, the system can generate executable code/logic, which can be executed or applied to subsequent similar data sets.