The unique constraint prevents two records from having identical values in a column. in the customers table, for example, you might want to prevent two or more people from having an identical age. example. for example, the following sql query creates a new table called customers and adds five columns.. Since the stack overflow post you linked to explains how the unique key constraint is implemented using a unique index, so the two are the same for practical purposes, i'll skip that part and try to explain how a unique index improves query performance.. Query below returns all primary keys and unique key constraints and unique indexes **on **tables and views in sql server database.. check out also list of unique keys.. query.
Unique key in sql with sql, tutorial, examples, insert, update, delete, select, join, database, table, join. Sql unique constraint. the unique constraint ensures that all values in a column are different. both the unique and primary key constraints provide a guarantee for uniqueness for a column or set. Unique key constraint sql query a job portal http://www.interviewdot.com http://www.interviewdot.com http://www.interviewdot.com one click dream job - http:/....
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