Sunday, 26 January 2014

Explain: a.) Integrity constraint. b.) COALESCE function

a.) Integrity constraint.
- It is a declaration defined in a business rule for a table column.
- Integrity constraint ensures the accuracy and consistency of data in a database.
- It is of three types - namely - Domain Integrity, Referential Integrity and Domain Integrity.





b.) COALESCE function

- This function is used to return the value which is set not to be null in the list.
- Incase all values in the list are null the coalesce function will return NULL.
- Its representation:
Coalesce(value1, value2, value3,…)

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