Question

I need to count the unique instances in a field, then sort the counts by their dates and am trying to do it all in one query using SQL.

I have table that looks like this:

Date...........Defect_Code..........
2016-06-12     Machine Issue
2016-06-12     Broken
2016-06-12     null
2016-06-13     Machine Issue
2016-06-13     Machine Issue
2016-06-14     Crack
2016-06-14     Crack

I would like for this to be sorted by date while counting the instance of each Defect_Code resulting in a table looking similar to

Date............Count(Machine Issue)...Count(Broken)...Count(Crack)...Count(null)....
2016-06-12......1......................1...............0..............1..............
2016-06-13......2......................0...............0..............0..............
2016-06-14......0......................0...............3..............0..............

Thanks in advance for any help!

Answer 1

You can do this with conditional aggregation since the values for Defect_Code are consistent:

SELECT Date
     , COALESCE(SUM(CASE WHEN Defect_Code = 'Machine Issue' THEN 1 END),0) AS 'Count(Machine Issue)'
     , COALESCE(SUM(CASE WHEN Defect_Code = 'Broken' THEN 1 END),0) AS 'Count(Broken)'
     , COALESCE(SUM(CASE WHEN Defect_Code = 'Crack' THEN 1 END),0) AS 'Count(Crack)'
     , COALESCE(SUM(CASE WHEN Defect_Code IS NULL THEN 1 END),0) AS 'Count(Null)'
FROM YourTable
GROUP BY Date
ORDER BY Date

Need to count unique occurrences in a column, and group the result by date

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