1. EmpNoENameMach_NoType E1BloggsM2Lathe E2SmithM1Drill E3JonesM3Squeeper E4CarterM4Moulder 1:1 Obligatory:Obligatory Machine Employee 11 Deriving tables from the ERD – examples used in lecture

2. EmpNoENameMach_NoType E1BloggsM2Lathe E2Smith E3Jones E4CarterM4Moulder 1:1 Non-Obligatory:Obligatory EmployeeMachine 11

3. EmpNoENameMach_NoType E1BloggsM2Lathe E2Smith E3JonesM3Squeeper M4Moulder M5Grinder E4Carter 1:1 Non-Obligatory:Non-Obligatory EmployeeMachine 11

4. EmpNoENameMach_NoType E1BloggsM2Lathe E2SmithM1Drill E1BloggsM3Squeeper E1BloggsM4Moulder 1:m Obligatory:Obligatory EmployeeMachine 1m Mach_NoTypeEmpNo M2LatheE1 M1DrillE2 M3SqueeperE1 M4MoulderE1 EmpNoEName E1Bloggs E2Smith But as two tables – this would give:

5. EmpNoEName E1Bloggs E2Smith Mach_NoTypeEmpNo M2Lathe M1DrillE2 M3SqueeperE1 M4Moulder 1:m Many end Non-Obligatory EmployeeMachine 1m Get blanks in last column. We could end up with a lot of these depending on type of data, so to eliminate it we define a third table.

6. EmpNoEName E1Bloggs E2Smith Mach_NoType M2Lathe M1Drill M3Squeeper M4Moulder Mach_NoEmpNo M1E2 M3E1 This is also be a candidate for ‘flexing’ – refer to notes/later lecture (i.e. observing that in theory there should be 3 tables, but only defining 2). The three tables would be: