hi,
can i put multiple values in a single attribute?
If its possible, how can i do that using sdb explorer?

Yes.. you can. Follow these steps.
1> Select the row and Right click for which you would like to add multiple values for an attribute.
2> Select "Update Item Row" option.
3> It will list all attribute and value(s).
4> Remove the value of an attribute, for which you would like to add multiple values, in Table having Attribute, Values and Replace columns over "Update Item Row" panel.
5> Enter the new value which you would like to add.
6> Uncheck the check box of "Replace" for the newly added value , that is being checked by-default.
7> Hit "Update" button. Soon you will find multiple values for an attribute by coma separator in main table.

Thanks