Interview Answer

Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are–by definition–not smart enough to debug it. Brian Kernighan

find duplicate records with the number they are duplicated?

April 12, 2016 7:26 pm

Comments



find duplicate records with the number they are duplicated?



												desc HR.employees;
												
												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 employee_id, count (*) as num_records
													from  HR.employees  
													group by employee_id  
													having count (*) > 1;
																    

Comments



Please login to add comments.