Change Columns Name dynamically in sql

Question

I have a query result like this :

Date       User1 User2 User3 ....
----------------------------------
1/1/2000   55     78    98   ...
1/1/2001   26     33    5         


        

Answer 1

SQL Fiddle

Schema Setup:

create table history (date datetime, name varchar(10), value int);
insert history values
 ('20130101', 'user1', 123),
 ('20130101', 'user2', 124),
 ('20130101', 'user3', 125),
 ('20130102', 'user1', 223),
 ('20130102', 'user3', 223),
 ('20130103', 'user2', 323);

create table colours (name varchar(10), colour_name varchar(10));
insert colours values
 ('user1', 'blue'),
 ('user2', 'green'),
 ('user3', 'brown');

Query:

DECLARE @scols nvarchar(max),
        @cols AS NVARCHAR(MAX),
        @query AS NVARCHAR(MAX);

select @cols = STUFF((
  SELECT ',' + QUOTENAME(C.Name)  
  from (select distinct name from [History]) C
  ORDER BY C.Name
  FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'),1,1,'');

select @scols = STUFF((
  SELECT ',' + QUOTENAME(Name) + ' AS ' + QUOTENAME(colour_Name)  
  from (select distinct c.name, x.colour_name
        from [History] C
        JOIN colours x on x.name = c.name) y
  ORDER BY Name
  FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'),1,1,'');

set @query = '
    SELECT [Date],' + @scols +' 
    from (
        select [Date], Name, Value
        from [History]
         ) x
    pivot 
         (
        max(value)
        for Name in (' + @cols + ')
         ) p ';

-- print @query --<< uncomment this line to see the query that gets generated
exec (@query);

Results:

|                           DATE |   BLUE |  GREEN |  BROWN |
-------------------------------------------------------------
| January, 01 2013 00:00:00+0000 |    123 |    124 |    125 |
| January, 02 2013 00:00:00+0000 |    223 | (null) |    223 |
| January, 03 2013 00:00:00+0000 | (null) |    323 | (null) |