在一列到多列中选择不同的值

Question

I have the following data: column 1 with many category and column 2 with values for each category. I need to convert or pivot this information to show each value for category group across multiple columns.

col1      col2
----------------
1         a    
2         b 
2         c
2         d
3         e
3         f 
4         g
4         h

And need this result:

col1      col2     col3     col4   col5   col6   
-----------------------------------------------   
1         a
2         b         c       d
3         e         f 
4         g         h

There are no more than seven values per tb1 count(column 2) group(column 1). All values from tb1 column 2 are different and about + 50 records.

Answer 1

You want to pivot your table, but your table doesn't currently contain the field that you want to pivot on ("col1", "col2", "col3", etc...). You need a row number, partitioned by col1. The Jet database does not provide a ROW_NUMBER function, so you have to fake it by joining the table to itself:

select t1.col1, t1.col2, count(*) as row_num
from [Sheet1$] t1
inner join [Sheet1$] t2 on t2.col1 = t1.col1 and t2.col2 <= t1.col2
group by t1.col1, t1.col2

Now you can pivot on row_num :

transform Min(x.col2) select x.col1
from(
    select t1.col1, t1.col2, count(*) as row_num
    from [Sheet1$] t1
    inner join [Sheet1$] t2 on t2.col1 = t1.col1 and t2.col2 <= t1.col2
    group by t1.col1, t1.col2
    )  x
group by x.col1
pivot x.row_num