SQL UNION Operator

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what is use of union and union all Operator in sqlserver.
  1. Post:281

    Points:2003
    Re: SQL UNION Operator

    The UNION operator is used to combine the result-set of two or more SELECT statements.

    Notice that each SELECT statement within the UNION must have the same number of columns. The columns must also have similar data types. Also, the columns in each SELECT statement must be in the same order.

    SQL UNION Syntax

    SELECT column_name(s) FROM table1
    UNION
    SELECT column_name(s) FROM table2;

    Note: The UNION operator selects only distinct values by default.

    SQL UNION ALL Syntax

    SELECT column_name(s) FROM table1
    UNION ALL
    SELECT column_name(s) FROM table2;

    Note : The UNION operator selects All (duplicate values also) values by default.

    For Exp:

    Union

    SELECT City FROM Customer
    
    UNION

    SELECT City FROM Supplier

    ORDER BY City

    Result :

      

     


     

    Result:

     

     

     Union All

    SELECT City FROM Customer
    
    UNION
    SELECT City FROM Supplier
    ORDER BY City

     

      Modified On Apr-10-2018 05:24:06 AM

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