Oracle Magazine, March/April 2019
Database Developer and DBA ETL ORACLE MAGAZINE MARCH APRIL 2019 110 1 HASH GROUP BY 2 MERGE JOIN CARTESIAN 3 TABLE ACCESS FULL DEPT 4 BUFFER SORT 5 TABLE ACCESS FULL EMP Even without GROUP BY aggregations a common but erroneous approach I see to fixing SQL statements that have missing join conditions or an incorrect order of operations is adding the DISTINCT keyword Listing 10 starts with the query in Listing 8 but just lists employee details without the GROUP BY Listing 10 Employee details still with the missing join predicates SQL select e 2 from EMP e 3 DEPT d 4 where e JOB SALESMAN 5 and d LOC NORTH EMPNO ENAME JOB MGR HIREDATE 7499 ALLEN SALESMAN 7698 20 FEB 81 7499 ALLEN SALESMAN 7698 20 FEB 81 7499 ALLEN SALESMAN 7698 20 FEB 81 7499 ALLEN SALESMAN 7698 20 FEB 81
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