Databases Reference
In-Depth Information
B.3 Step 3
Finally, form the table:
projSName(SUPPLIERS/TYPE) - projSName (R)
That is, subtract the table in Step 2 from the first column of the SUPPLIERS/TYPE table.
This gives the suppliers that supply all four types of wood, as Table B-6 illustrates.
Table B-6. SUPPLIER/TYPE รท WOOD
SName
J
ones Wood Supply
O
range Coast
