Interview Answer

The bearing of a child takes nine months, no matter how many women are assigned. Many software tasks have this characteristic because of the sequential nature of debugging. Fred Brooks

find duplicate records with the number they are duplicated?

January 1, 1970 12:00 am

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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;
																    

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