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sql-serverpivotunpivot

SQL Server Pivot using multiple sets of columns


From a table like this:

CREATE TABLE dbo.mytable 
(
     [ID] int, 
     [Category] INT, 
     [Lh] varchar(30), 
     [Sev] INT, 
     [Risk] INT
)

insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (5, 2, 'Impossible', 4, 10)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 2, 'Unlikely', 3, 13)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 3, 'Possible', 3, 18)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 5, 'Likely', 3, 23)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 6, 'Possible', 3, 18)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (7, 2, 'Impossible', 5, 15)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (8, 2, 'Very Unlikely', 5, 20)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (9, 2, 'Unlikely', 6, 30)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (10, 2, 'Impossible', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (10, 6, 'Impossible', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 1, 'Impossible', 4, 10)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 2, 'Very Unlikely', 5, 20)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 4, 'Impossible', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (13, 2, 'Impossible', 6, 21)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (14, 2, 'Impossible', 6, 21)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (15, 1, 'Very Unlikely', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (15, 2, 'Impossible', 5, 15)

I am trying to create a result set that looks like this (bearing in mind that there are any number of Categories possible, but always 3 components to every category):

ID  Cat_1_Lh    Cat_1_Sev   Cat_1_Risk  Cat_2_Lh    Cat_2_Sev   Cat_2_Risk  Cat_3_Lh    Cat_3_Sev   Cat_3_Risk  Cat_4_Lh    Cat_4_Sev   Cat_4_Risk  Cat_5_Lh    Cat_5_Sev   Cat_5_Risk  Cat_6_Lh    Cat_6_Sev   Cat_6_Risk
5                                       Impossible      4           10                                              
6                                       Unlikely        3           13      Possible        3           18                                          Likely          3           23      Possible        3           18
7                                       Impossible      5           15                                              
8                                       Very Unlikely   5           20                                              
9                                       Unlikely        6           30                                              
10                                      Impossible      3           6                                                                                                                   Impossible      3            6
12  Impossible      4           10      Very Unlikely   5           20                                          Impossible      3           6                       
13                                      Impossible      6           21                                              
14                                      Impossible      6           21                                              
15  Very Unlikely   3           6       Impossible      5           15                                              

I have looked at and tried to modify a range of pivot and unpivot solutions presented here, with dynamic and static column definitions but none of them look like they have the remotest chance of working so I don't know which ones to suggest can be leveraged into a solution.

I would very appreciate some guidance as to which process/mechanism would be best suited to this.

Thanks in advance.


Solution

  • One naive way to solve this problem is to write query like this

    ;with cte_lh as (
    select Id, max([1]) as Cat_1_lh,max([2]) as Cat_2_lh,max([3]) as Cat_3_lh,max([4]) as Cat_4_lh,max([5]) as Cat_5_lh,max([6]) as Cat_6_lh from mytable 
    pivot(max(Lh) for Category in ([1],[2],[3],[4],[5],[6])) as p
    group by id
    ), cte_sev as (
    select id,  max([1]) as Cat_1_Sev,max([2]) Cat_2_Sev,max([3]) Cat_3_Sev,max([4]) Cat_4_Sev,max([5]) Cat_5_Sev,max([6]) Cat_6_Sev from mytable
    pivot (max(sev) for category in ([1],[2],[3],[4],[5],[6])) as p
    group by id
    ), cte_risk as (
    select id,  max([1]) Cat_1_Risk,max([2]) Cat_2_Risk,max([3]) Cat_3_Risk,max([4]) Cat_4_Risk,max([5]) Cat_5_Risk,max([6]) Cat_6_Risk from mytable
    pivot (max(risk) for category in ([1],[2],[3],[4],[5],[6])) as p
    group by id
    ) select * from cte_lh lh join cte_sev sev on lh.id = sev.id
    join cte_risk risk on lh.id = risk.id
    

    We can create columns in dynamic sql and add columns and create dynamic sql if your column list is varying..