Problem relating tables : Many to many

I'm trying to create a point map of locations, the problem is that I can't join or relate the nonspatial data I have.
Each location has an i.d. number that is not in the layer attribute table, but the site location number matches. There is a ratio of about 7:3 from the nonspatial table locations to the layer attribute table
I.e:

Excel nonspatial table

Column 1
id
id-389
id-679
id-45
id-1207

Column 2
locationid
Lo-15
Lo-15
Lo-10
Lo-15

Layer attribute table

Column 1
id
id-786
id-245
id-447
id-2364

Column 2
locationid
Lo-15
Lo-25
Lo-15
Lo-30

Column 3 and 4 contain Shape_Length and Shape_Area
What other method could I try to add the locations to the map?