The above stated problem can be represented as the figure below. Let us say we have a table consisting of two fields as NAME and ID and has been maintained as follows.

Figure 1

In order to find out how many names are there in the NAME field we cannot put sum function across it. This is because by putting sum across the NAME we will find only 5 instead of 17.

Listing 1

select sum(length(name) - length(translate(name,' ,',' '))+1) NAMES 
from multiple_id;

Figure 2