What is COALESCE and CHECK constraint in SQL server?


Posted On: Feb 22, 2018


    1 Answer Written

  •  devquora
    Answered by Sam Chadwick

    SQL Coalesce constraint: It is a function of the SQL server which is used for handling the NULL values. By using this function at the time of evaluation the null values will be replaced by the defined values.


    COALESCE (expression [ 1…..n]) 

    To use coalesce constraint it is needed that all expressions should be of the same type of data. Multiple expressions are acceptable by this function of SQL.

    SQL CHECK constraint: The SQL CHECK constraint is used for specifying the values of the column. It is needed that it satisfies the Boolean expression. The definition of check constraint always comes after the data type along with a keyword CHECK.

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