Consider the following database:

Apply following query by two different methods given below and show the intermediate relations. Also describe which one of the methods is good in query optimization context and why?

Query

SELECT E.Lname, E.Bdate, D.Mgr_ssn FROM EMPLOYEE AS E, DEPARTMENT AS D WHERE E.Salary >= 30000 AND D.Dname = Research

AND E.Dno = D.Dnumber;

Method1:

Apply Join first and then Selection according to given conditions

Methdo2:

Apply Selection first and then Join according to given conditions

EMPLOYEE Fname Minit Lname John FranklinT Wong 333445555 1955-12-08 638 Voss, Houston, TXM 40000 888665555 5 Alicia JenniferSWallace 9876543211941-06-20 291 Berry, Bellaire, TX Ramesh K Narayan 666884444 1962-09-15 975 Fire Oak, Humble, TX M 38000 333445555 5 Joyce AhmadVJabbar 987987987 1969-03-29 980 Dallas, Houston, TXM 25000 9876543214 James E Borg 888665555 1937-11-10 450 Stone, Houston, TX M 55000 NULL Sex Salary Super ssn Dno Ssn Bdate Address B Smith 123456789 1965-01-09 731 Fondren, Houston, TX M 30000 333445555 5 JZelaya 999887777 1968-01-19 3321 Castle, Spring, TX F 25000 987654321 4 F 43000 888665555 4 A English 453453453 1972-07-315631 Rice, Houston, TXF 25000 333445555 5 DEPARTMENT DEPT LOCATIONS Dlocation Houston Stafford Bellaire Sugarland Houston Dname Dnumber Dnumber Research Administration Headquarters Mgr ssn 333445555 987654321 888665555 Mgr_start_date 988-05-22 1995-01-01 1981-06-19 4 4