How to use subquery in USQL? - subquery

Question

I am getting complilation error while using follwowing query in u-sql:
#CourseDataExcludingUpdatedCourse = SELECT * FROM #CourseData AS cd
WHERE cd.CourseID NOT IN (SELECT CourseID FROM #UpdatedCourseData);
It is not allowing me to use NOT IN Clause in subquery. I want to show all those records which are not present in #UpdatedCourseData.
How can I achieve this in U-SQL?

Answer 1

In U-SQL NOT EXISTS is implemented as ANTISEMIJOIN, something like this:
#CourseDataExcludingUpdatedCourse =
SELECT cd.*
FROM #CourseData AS cd
ANTISEMIJOIN
#UpdatedCourseData AS us
ON cd.courseId == us.courseId;
See here for more info:
https://msdn.microsoft.com/en-us/library/azure/mt621330.aspx

Answer 2

#employees =
SELECT * FROM
( VALUES
(1, "Noah", 100, (int?)10000, new DateTime(2012,05,31)),
(2, "Sophia", 100, (int?)15000, new DateTime(2012,03,19)),
(3, "Liam", 100, (int?)30000, new DateTime(2014,09,14)),
(4, "Amy", 100, (int?)35000, new DateTime(1999,02,27)),
(5, "Justin", 600, (int?)15000, new DateTime(2015,01,12)),
(6, "Emma", 200, (int?)8000, new DateTime(2014,03,08)),
(7, "Jacob", 200, (int?)8000, new DateTime(2014,09,02)),
(8, "Olivia", 200, (int?)8000, new DateTime(2013,12,11)),
(9, "Mason", 300, (int?)50000, new DateTime(2016,01,01)),
(10, "Ava", 400, (int?)15000, new DateTime(2014,09,14))
) AS T(EmpID, EmpName, DeptID, Salary, StartDate);
#departments =
SELECT * FROM
( VALUES
(100, "Engineering"),
(200, "HR"),
(300, "Executive"),
(400, "Marketing"),
(500, "Sales"),
(600, "Clerical"),
(800, "Reserved")
) AS T(DeptID, DeptName);
/* T-SQL; Using a subquery with IN
SELECT *
FROM #employees
WHERE DeptID IN
(SELECT DeptID FROM #departments WHERE DeptName IN ('Engineering', 'Executive'));
*/
// U-SQL; Using SEMIJOIN
#result =
SELECT *
FROM #employees AS e
LEFT SEMIJOIN (SELECT DeptID FROM #departments WHERE DeptName IN ("Engineering", "Executive")) AS sc
ON e.DeptID == sc.DeptID;
OUTPUT #result
TO "/Output/ReferenceGuide/Joins/SemiJoins/SubqueryIN.txt"
USING Outputters.Tsv(outputHeader: true);
/* T-SQL; Using a subquery with NOT IN
SELECT *
FROM #employees
WHERE DeptID NOT IN
(SELECT DeptID FROM #departments WHERE DeptName IN ('Engineering', 'Executive'));
*/
// U-SQL; Using ANTISEMIJOIN
#result =
SELECT *
FROM #employees AS e
LEFT ANTISEMIJOIN (SELECT DeptID FROM #departments WHERE DeptName IN ("Engineering", "Executive")) AS sc
ON e.DeptID == sc.DeptID;
OUTPUT #result
TO "/Output/ReferenceGuide/Joins/AntiSemiJoins/SubqueryNOTIN.txt"
USING Outputters.Tsv(outputHeader: true);
// BONUS: Switch "LEFT" to "RIGHT" in the above examples and observe the results.