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First Normal Form (1NF)

  • A relation will be 1NF if it contains an atomic value.
  • It states that an attribute of a table cannot hold multiple values. It must hold only single-valued attribute.
  • First normal form disallows the multi-valued attribute, composite attribute, and their combinations.

Example: Relation EMPLOYEE is not in 1NF because of multi-valued attribute EMP_PHONE.

EMPLOYEE table:

EMP_ID EMP_NAME EMP_PHONE EMP_STATE
14 John 7272826385,
9064738238
UP
20 Harry 8574783832 Bihar
12 Sam 7390372389,
8589830302
Punjab

The decomposition of the EMPLOYEE table into 1NF has been shown below:

EMP_ID EMP_NAME EMP_PHONE EMP_STATE
14 John 7272826385 UP
14 John 9064738238 UP
20 Harry 8574783832 Bihar
12 Sam 7390372389 Punjab
12 Sam 8589830302 Punjab

Next TopicDBMS 2NF




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