SQL Create new column(s) if row value exists - sql

Question

I have a large data set that looks like the below:
NAME Value
Dan 1
Dan 92
Dan A4
Steve 1
Steve B10
John 4
I'm trying to convert it into a table like:
Name Value1 Value2 Value3
Dan 1 92 B10
Steve 1 B10 Null
John 4 Null Null
So there is an unknown amount of rows and I'd like to create a new column for every value when it exists. Anyone have an idea of how to do this in SQL?

Answer 1

The example you provided would work perfectly using PIVOT, but you need to supply a category to the values to do the pivot.
e.g.
NAME Category Value
Dan Value1 1
Dan Value2 92
Dan Value3 A4
Steve Value1 1
Steve Value3 B10
John Value1 4
Then your results would be like this
Name Value1 Value2 Value3
Dan 1 92 A4
Steve 1 NULL B10
John 4 NULL NULL
Here's Microsoft's documentation:
https://learn.microsoft.com/en-us/sql/t-sql/queries/from-using-pivot-and-unpivot?view=sql-server-ver15
To do this dynamically, please read this post. It handles the same situation well.
SQL Server dynamic PIVOT query?

Answer 2

To pivot data you need something to pivot it by.
In this case it can be generated using ROW_NUMBER.
For example:
--
-- sample data
--
create table yourlargetable (
id int identity(1,1) primary key,
name nvarchar(30),
value nvarchar(30)
);
insert into yourlargetable (name, value) values
('jane', 'val1'), ('jane', 'val2'), ('jane', 'val3'),
('john', 'val4'), ('john', 'val5');
--
-- declare a few variables
--
declare #DynSql nvarchar(max);
declare #Cols nvarchar(max);
declare #ColTotal int;
--
-- how many columns are needed
--
select top 1 #ColTotal = count(*)
from yourlargetable
group by name
order by count(*) desc;
--
-- generate a string with column names
--
with RCTE_NUMS as
(
select 1 as n
union all
select n+1
from RCTE_NUMS
where n < #ColTotal
)
select #Cols = concat(#Cols+', ', quotename(concat('Value', n)))
from RCTE_NUMS
order by n;
--
-- create the dynamic sql string
--
set #DynSql = 'select *'+ char(10) +
'from ('+
'select name, value '+ char(10) +
', concat(''Value'', row_number() over (partition by name order by value)) col '+ char(10) +
'from yourlargetable) s'+ char(10) +
'pivot (max(value) '+ char(10) +
'for col in ('+ #Cols +')) p'+ char(10) +
'order by name';
-- select #DynSql;
--
-- run the dynamic sql
--
exec sp_executesql #DynSql;
Returns:
name Value1 Value2 Value3
jane val1 val2 val3
john val4 val5 NULL