SQL Server convert a table column values to names and assign 0 to the new columns if no value for a column

Question

I would like to transform a table from rows to columns in SQL Server.

Given table1:

id value1  value2
 1  name1    9
 1  name1    26
 1  name1    15
 2  name2    20
 2  name2    18
 2  name2    61

I need a table like:

id name1 name2 
1  9      0 
1  26     0 
1  15     0 
2  0     20 
2  0     18
2  0     61

Can pivot help here? An efficient way is preferred to do the convert because the table is large.

I have tried:

select
    id, name1, name2
from
    (select 
         id, value1, value2
     from table1) d
pivot
( 
   max(value2)
   for value1 in (name1, name2)
) piv;

But, it cannot provide all rows for same ID to combine with 0s.

Thanks

Answer 1

The 'secret' is to add a column to give uniqueness to each row within your 'nameX' groups. I've used ROW_NUMBER . Although PIVOT requires an aggregate, with our 'faked uniqueness' MAX, MIN etc will suffice. The final piece is to replace any NULL s with 0 in the outer select.

(BTW, we're on 2014 so I can't test this on 2008 - apologies)

SELECT * INTO #Demo FROM (VALUES
 (1,'name1',9),
 (1,'name1',26),
 (1,'name1',15),
 (2,'name2',20),
 (2,'name2',18),
 (2,'name2',61)) A (Id,Value1,Value2)



 SELECT
    Id
   ,ISNULL(Name1, 0) Name1
   ,ISNULL(Name2, 0) Name2
 FROM
    ( SELECT
        ROW_NUMBER() OVER ( PARTITION BY Id ORDER BY Id ) rn
       ,Id
       ,Value1
       ,Value2
      FROM
        #Demo ) A 
  PIVOT ( MAX(Value2) FOR Value1 IN ( [Name1], [Name2] ) ) AS P;

Id          Name1       Name2
----------- ----------- -----------
1           9           0
1           26          0
1           15          0
2           0           20
2           0           18
2           0           61

Answer 2

you can do case based aggregation with group by

SQL Fiddle

select id, 
   max(case when value1 ='name1' then value2 else 0 end) as name1,
   max(case when value1 ='name2' then value2 else 0 end) as name2
from Table1
group by id, value1, value2