Interview Answer

Selecting ODD or EVEN rows from a table

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Selecting ODD or EVEN rows from a table

												desc suppliers;
												
												Name           Null     Type         
												-------------- -------- ------------ 
												EMPLOYEE_ID    NOT NULL NUMBER(6)    
												FIRST_NAME              VARCHAR2(20) 
												LAST_NAME      NOT NULL VARCHAR2(25) 
												EMAIL          NOT NULL VARCHAR2(25) 
												PHONE_NUMBER            VARCHAR2(20) 
												HIRE_DATE      NOT NULL DATE         
												JOB_ID         NOT NULL VARCHAR2(10) 
												SALARY                  NUMBER(8,2)  
												COMMISSION_PCT          NUMBER(2,2)  
												MANAGER_ID              NUMBER(6)    
												DEPARTMENT_ID           NUMBER(4)  

												

Solution

   					 
												-- select the odd rows using mod funcation
												select * from
												(select employee_id, first_name, last_name, salary, rownum rn
												from hr.employees
												order by employee_id)
												where  mod (rn, 2) <> 0;


												-- select the Even Rows using mod funcation
												select * from
												(select employee_id, first_name, last_name, salary, rownum rn
												from hr.employees
												order by employee_id)
												where  mod (rn, 2) = 0;