In database design: Why do spurious tuples occur in the result of joining the EM

Question

In database design:

Why do spurious tuples occur in the result of joining the EMP PROJl and EMP_LOCS relations in Figure 14.5 (result shown in Figure 14.6, figure below)? Plocation Bellaire Bellaire Ename Smith, John B Ssn 123456789 123456789 123456789 123456789 123456789 666884444 666884444 453453453 453453453 453453453 453453453 453453453 333445555 333445555 333445555 333445555 333445555 333445555 333445555 333445555 PnumberHourS Pnam 32.5 ProductX 32.5 ProductX English, Joyce A. 7.5ProductYSugarland |Smith, John B 7.5ProductYSugarlandEnglish, Joyce A. 40.00ProductY Sugarland Wong, Franklin T 40.00ProductzH 20.00ProductzH 20.00Productx 20.00Productx 20.00 ProductY Sugarland Smith, John B 20.00 ProductY Sugarland English, Joyce A. 20.00 ProductY Sugarland Wong, Franklin T 10.00 ProductY Sugarland Smith, John B 10.00 ProductY Sugarland English, Joyce A. 10.00 ProductY Sugarland Wong, Franklin T 10.00ProductzH 10.00ProductxH 10.00Productx 10.00ProductxH 10.00ProductxH Houston Narayan, Ramesh K. Houston Wong, Franklin T Bellaire Bellaire Smith, John B English, Joyce A. 10 20 20 Houston Narayan, Ramesh K. Houston Wong, Franklin T Stafford Wong, Franklin T Houston Narayan, Ramesh K. Houston Wong, Franklin T

Explanation / Answer

spurious tuples occurs in the result of the join query if the tables done not have any primary key or foreign key containts.In this case EMP_PROJ1 and EMP_LOCS does not have any primary key and foreign key contrains so the result of joining have spurious tuples. So the data duplication happens in the query.

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