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== (Equals) (U-SQL)

Michael Rys|Last Updated: 5/15/2018
|
4 Contributors

Compares the equality of two expressions (a comparison operator). U-SQL uses C# null semantics which is 2-valued and not 3-valued as in ANSI SQL.

Syntax
Equals_Operator :=                                                                                       
    expression == expression.

Semantics of Syntax Elements

  • expression
    Is any valid expression. If the expressions are not of the same data type, the data type for one expression must be implicitly convertible to the data type of the other.

Result Types

Boolean

Examples

  • The examples can be executed in Visual Studio with the Azure Data Lake Tools plug-in.
  • The scripts can be executed locally. An Azure subscription and Azure Data Lake Analytics account is not needed when executed locally.
@somePeople = 
    SELECT * FROM 
        ( VALUES
        (1, "Noah",    100, (int?)10000, new DateTime(2012,05,31), "cell:030-0074321,office:030-0076545"),
        (2, "Sophia",  100, (int?)15000, new DateTime(2012,03,19), "cell:(5) 555-4729,office:(5) 555-3745"),
        (3, "Liam",    100, (int?)30000, new DateTime(2014,09,14), ""),
        (6, "Emma",    200, (int?)8000,  new DateTime(2014,03,08), (string)null),
        (7, "Jacob",   200, (int?)8000,  new DateTime(2014,09,02), "cell:(5) 555-3932"),
        (8, "Olivia",  200, (int?)8000,  new DateTime(2013,12,11), "cell:88.60.15.31,office:88.60.15.32"),
        (9, "Mason",   300, (int?)50000, new DateTime(2016,01,01), "cell:(91) 555 22 82,office:(91) 555 91 99, home:(425) 555-2819"),
        (10, "",       400, (int?)15000, new DateTime(2014,09,14), "cell:91.24.45.40,office:91.24.45.41"),
        (11, "Ethan ", 400, (int?)null,  new DateTime(2015,08,22), "cell:(604) 555-4729,office:(604) 555-3745")
        ) AS T(EmpID, EmpName, DeptID, Salary, StartDate, PhoneNumbers);


/********** Working with null **********/
// Does return a record (non ANSI  behavior)
@result1 = SELECT * FROM @somePeople WHERE Salary == null;
OUTPUT @result1 TO "/Output/ReferenceGuide/Operators/Comparison/example1.txt" USING Outputters.Tsv();

// Does return a record
@result2 = SELECT * FROM @somePeople WHERE Salary == (int?)null;
OUTPUT @result2 TO "/Output/ReferenceGuide/Operators/Comparison/example2.txt" USING Outputters.Tsv();

// Does return a record
@result3 = SELECT * FROM @somePeople WHERE Salary IS NULL;
OUTPUT @result3 TO "/Output/ReferenceGuide/Operators/Comparison/example3.txt" USING Outputters.Tsv();

// Result set includes a record with a null salary (non ANSI  behavior)
@result4 = SELECT * FROM @somePeople WHERE Salary != 8000;
OUTPUT @result4 TO "/Output/ReferenceGuide/Operators/Comparison/example4.txt" USING Outputters.Tsv();
/***************************************/


// Other examples
@result5 = SELECT * FROM @somePeople WHERE EmpName.TrimEnd() == "Ethan";
OUTPUT @result5 TO "/Output/ReferenceGuide/Operators/Comparison/example5.txt" USING Outputters.Tsv();

@result6 = SELECT * FROM @somePeople WHERE EmpName == "Ethan ";
OUTPUT @result6 TO "/Output/ReferenceGuide/Operators/Comparison/example6.txt" USING Outputters.Tsv();

// Empty space is not equal to null
@result7 = SELECT * FROM @somePeople WHERE EmpName == null;
OUTPUT @result7 TO "/Output/ReferenceGuide/Operators/Comparison/example7.txt" USING Outputters.Tsv();

// Empty space is not equal to white space
@result8 = SELECT * FROM @somePeople WHERE EmpName == " ";
OUTPUT @result8 TO "/Output/ReferenceGuide/Operators/Comparison/example8.txt" USING Outputters.Tsv();

See Also

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