how to replace specific character , if possible using sed

My script is extracting data from SQl session, however sometimes the result contains one or multiple space after/before any numerical value.
e,g .

"123","1 34","1 3 45", "43 5"

How to remove these unwanted spaces..so that I can get the following result :
"123","134",1345","435"

 sed 's/ //' filename

should delete spaces i think.
u can also use

cat file | tr -d' '

just a guess..(im a noob).