Reg: Merging Rows

[usha hive]

Hi,

I am trying to merge few rows in to 1 row. I am stuck. Please help me.

Example
id  col1      col2      col3        col4
1   44       NULL    NULL    NULL
1  NULL     37       NULL     NULL
1  NULL    NULL   88        NULL
1  NULL    NULL   NULL    99

to
id  col1      col2      col3        col4
1     44          37        88           99

Thanks,
Usha