sql server - Understanding PIVOT function in T-SQL -

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i new sql.

i have table this:

id | teamid | userid | elementid | phaseid | effort ----------------------------------------------------- 1  |   1    |  1      |   3       |  5     |   6.74 2  |   1    |  1      |   3       |  6     |   8.25 3  |   1    |  1      |   4       |  1     |   2.23 4  |   1    |  1      |   4       |  5     |   6.8 5  |   1    |  1      |   4       |  6     |   1.5

and told data this

elementid | phaseid1 | phaseid5 | phaseid6 --------------------------------------------     3     |   null   |   6.74   |   8.25     4     |   2.23   |   6.8    |   1.5

i understand need use pivot function. can't understand clearly. great if can explain in above case.(or alternatives if any)

a pivot used rotate data 1 column multiple columns.

for example here static pivot meaning hard code columns want rotate:

create table temp (   id int,   teamid int,   userid int,   elementid int,   phaseid int,   effort decimal(10, 5) )  insert temp values (1,1,1,3,5,6.74) insert temp values (2,1,1,3,6,8.25) insert temp values (3,1,1,4,1,2.23) insert temp values (4,1,1,4,5,6.8) insert temp values (5,1,1,4,6,1.5)  select elementid   , [1] phaseid1   , [5] phaseid5   , [6] phaseid6 (   select elementid, phaseid, effort   temp ) x pivot (   max(effort)   phaseid in([1], [5], [6]) )p

here sql demo working version.

this can done through dynamic pivot create list of columns dynamically , perform pivot. 

declare @cols nvarchar(max),     @query  nvarchar(max);  select @cols = stuff((select distinct ',' + quotename(c.phaseid)              temp c             xml path(''), type             ).value('.', 'nvarchar(max)')          ,1,1,'')  set @query = 'select elementid, ' + @cols + '              (                 select elementid, phaseid, effort                 temp            ) x             pivot              (                  max(effort)                 phaseid in (' + @cols + ')             ) p '   execute(@query)

the results both:

elementid   phaseid1    phaseid5    phaseid6 3           null        6.74        8.25 4           2.23        6.8         1.5

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