I've been learning Oracle SQL recently and I came across the following code:
SELECT *
FROM employees outer_emps
WHERE (2-1) = (
SELECT COUNT(*)
FROM employees inner_emps
WHERE inner_emps.salary > outer_emps.salary
);
Could someone please help me understand the syntax?
It returns employees whose salary is the 2nd highest.
For example:
SQL> select ename, sal from emp order by sal;
ENAME SAL
---------- ----------
SMITH 840
JAMES 950
ADAMS 1100
WARD 1250
MARTIN 1250
MILLER 1300
TURNER 1500
ALLEN 1600
CLARK 2450
BLAKE 2850
JONES 2975
SCOTT 3000 --> SCOTT and FORD have the 2nd highest salary
FORD 3000 -->
KING 5000 --> KING has the highest salary
14 rows selected.
SQL> select ename, sal
2 from emp outer_emps
3 where 1 = (select count(*) from emp inner_emps
4 where inner_emps.sal > outer_emps.sal);
ENAME SAL
---------- ----------
SCOTT 3000
FORD 3000
SQL>
If you used <, you'd get the 2nd lowest salary (that's James because SMITH's salary is 840 - the lowest - and JAMES follows with 950):
SQL> select ename, sal
2 from emp outer_emps
3 where 1 = (select count(*) from emp inner_emps
4 where inner_emps.sal < outer_emps.sal);
ENAME SAL
---------- ----------
JAMES 950
SQL>
I'd probably do it as follows; that's easier to understand:
SQL> with temp as
2 (select ename, sal,
3 rank() over (order by sal desc) rnk
4 from emp
5 )
6 select ename,sal from temp
7 where rnk = 2;
ENAME SAL
---------- ----------
SCOTT 3000
FORD 3000
SQL>
Related
We have user details with a column of salary also, how can we print the user details with the maximum salary, I don't want to use the Subquery, and yeah how subquery will reduce the performance.
I know this query is wrong but I want something like this:
select User_name, user_id
from dual where salary=Max(salary);
Analytic functions help.
Using a CTE (which is kind of a subquery; don't be afraid of it, it doesn't bite and won't affect performance), query might look like this (based on sample Scott's schema):
SQL> select ename, sal from emp order by sal desc;
ENAME SAL
---------- ----------
KING 5000 --> this is the highest salary
FORD 3000 --> FORD and SCOTT share the 2nd place
SCOTT 3000
JONES 2975
BLAKE 2850
CLARK 2450
ALLEN 1600
TURNER 1500
MILLER 1300
WARD 1250 --> WARD and MARTIN are then 9th
MARTIN 1250
ADAMS 1100
JAMES 950
SMITH 800
14 rows selected.
Query is then
SQL> with temp as
2 (select ename,
3 dense_rank() over (order by sal desc) rnk
4 from emp
5 )
6 select ename
7 from temp
8 where rnk = 1;
ENAME
----------
KING
SQL>
Why dense_rank? Because two (or more) employees can have the same salary so they "rank" the same. For example, if you want to know whose salary is ranked as 9th, you'd
SQL> l8
8* where rnk = 1
SQL> c/1/9
8* where rnk = 9
SQL> /
ENAME
----------
WARD
MARTIN
SQL>
Query you suggested (although wrong, but - I got the idea) looks like this:
SQL> select ename
2 from emp
3 where sal = (select max(sal) from emp);
ENAME
----------
KING
SQL>
And yes, it affects performance because you're fetching data from the same emp table twice: once to find the max salary (in a subquery), and then in the main query to find who it belongs to.
I have a table with job, salary and date columns. I am writing the following query in PL/SQL, but I am getting an error
group function is not allowed here
delete employees where date = '06-05-2020 'and avg (salary)> 5500;
How can I solve this problem?
Your query makes no sense (to me, at least). What does that average salary represent? Whose average salary?
Here's an example based on Scott's EMP table; I'm going to delete employees who were hired on 3th of December 1981 and work in department whose employees' average salary is higher than 2000.
Sample data:
SQL> select deptno, ename, sal, hiredate from emp order by deptno, ename;
DEPTNO ENAME SAL HIREDATE
---------- ---------- ---------- ----------
20 ADAMS 1100 12.01.1983
20 FORD 3000 03.12.1981 --> this
20 JONES 2975 02.04.1981
20 SCOTT 3000 09.12.1982
20 SMITH 800 17.12.1980
30 ALLEN 1600 20.02.1981
30 BLAKE 2850 01.05.1981
30 JAMES 950 03.12.1981 --> this
30 MARTIN 1250 28.09.1981
30 TURNER 1500 08.09.1981
30 WARD 1250 22.02.1981
11 rows selected.
Averege salaries per department:
SQL> select deptno, avg(sal) avg_salary
2 from emp
3 group by deptno
4 order by avg_salary desc;
DEPTNO AVG_SALARY
---------- ----------
20 2175 --> higher than 2000
30 1566,66667
So: I'm looking for employees who work in department 20 (as only that department has average salaries higher than 2000) and who were hired on 03.12.1981 (James and Ford, but only Ford works in department 20):
SQL> delete from emp
2 where hiredate = date '1981-12-03'
3 and deptno in (select deptno
4 from emp
5 group by deptno
6 having avg(sal) > 2000
7 );
1 row deleted.
Is Ford still in there?
SQL> select * From emp where ename = 'FORD';
no rows selected
SQL>
Nope, deleted.
Now, your turn.
I was trying to print odd numbers of rows from my table without taking taking help of my numeric cloumns
when I try to execute this query I was getting only first row.
select * from emp3 where mod(rownum,2)=1;
emp3 is my table name.
and when I use my one of the numeric columns in place of rownum I was getting desired output.
select * from emp3 where mod(eid,2)=1 order by eid;
where eid is a numeric column in the table.
But what if do not have a numeric column and I want to print only odd number of rows from the table?
Help me!
Try to execute the below query
select * from (select rownum rn ,column from column_name) where mod(rn,2) <> 0
and please refer to this link for better understanding the concept of rownum https://www.youtube.com/watch?v=QMyw1jumGyQ
If the EID column isn't numeric, then use something that is. For example, ROW_NUMBER gives such an information:
SQL> with temp as
2 (select empno, ename, job sal,
3 row_number() over (order by null) rn
4 from emp
5 )
6 select *
7 from temp
8 where mod(rn, 2) = 1;
EMPNO ENAME SAL RN
---------- ---------- --------- ----------
7369 SMITH CLERK 1
7521 WARD SALESMAN 3
7654 MARTIN SALESMAN 5
7782 CLARK MANAGER 7
7839 KING PRESIDENT 9
7876 ADAMS CLERK 11
7902 FORD ANALYST 13
7 rows selected.
SQL>
Or even ROWNUM you already tried to use:
SQL> with temp as
2 (select empno, ename, job sal,
3 rownum rn
4 from emp
5 )
6 select *
7 from temp
8 where mod(rn, 2) = 1;
EMPNO ENAME SAL RN
---------- ---------- --------- ----------
7369 SMITH CLERK 1
7521 WARD SALESMAN 3
7654 MARTIN SALESMAN 5
7782 CLARK MANAGER 7
7839 KING PRESIDENT 9
7876 ADAMS CLERK 11
7902 FORD ANALYST 13
7 rows selected.
SQL>
currently I am using the below query to get the previous year’s bonus amount for the employees. But I am facing some issues, so I am trying to get the latest element entry value(screen entry value) for the element ‘xyz bonus’ using the RANK() function. Please help. Thanks.
Select
Pam.assignment_number,
Peev.screen_entry_value as bonus_amount
From
Per_all_assignments_m Pam,
Pay_element_entries_f peef,
Pay_element_types_tl petl,
Pay_element_entry_values_f peev
Where
Pam.Person_id=peef.person_id
and peef.element_type_id = petl. element_type_id
And peef.element_entry_id = peev. element_entry_id
And petl.language=‘US’
And to_char(peef.effective_start_date,’yyyy’)=(to_char(sysdate,’yyyy’)-1)
And to_char(peev.effective_start_date,’yyyy’)=(to_char(sysdate,’yyyy’)-1)
And petl.element_name = ‘xyz bonus’
As I don't have your tables, I'm using Scott's sample EMP table.
In there, rows sorted by salaries per department look like this:
SQL> select deptno,
2 ename,
3 sal,
4 rank() over (partition by deptno order by sal desc) rn
5 from emp
6 order by deptno,
7 sal desc;
DEPTNO ENAME SAL RN
---------- ---------- ---------- ----------
10 KING 10000 1
10 CLARK 2450 2
10 MILLER 1300 3
20 SCOTT 3000 1
20 FORD 3000 1
20 JONES 2975 3
20 ADAMS 1100 4
20 SMITH 920 5
30 BLAKE 2850 1
30 ALLEN 1600 2
30 TURNER 1500 3
30 MARTIN 1250 4
30 WARD 1250 4
30 JAMES 950 6
14 rows selected.
SQL>
If you want to fetch the highest salary per department, you'd then
SQL> select deptno, ename, sal
2 from (select deptno,
3 ename,
4 sal,
5 rank() over (partition by deptno order by sal desc) rn
6 from emp
7 )
8 where rn = 1;
DEPTNO ENAME SAL
---------- ---------- ----------
10 KING 10000
20 SCOTT 3000
20 FORD 3000
30 BLAKE 2850
SQL>
I guess that's what you are looking for.
Your query might then look like this:
Select
Pam.assignment_number,
Peev.screen_entry_value as bonus_amount,
rank() over (partition by pam.assignment_number order by peev.screen_entry_value desc) rn
From
...
Now, use it as an inline view (or a CTE) and fetch desired values.
If that's not what you are looking for, please, post sample data and desired result.
my query as follows.
WITH CTE AS
(
SELECT EmpID, EmpName, EmpSalary,
RN = ROW_NUMBER() OVER (ORDER BY EmpSalary DESC)
FROM dbo.Salary
)
SELECT EmpID, EmpName, EmpSalary
FROM CTE
WHERE RN = #8thRow
I am getting error as
Error report -
SQL Error: ORA-00923: FROM keyword not found where expected
00923. 00000 - "FROM keyword not found where expected".
Can someone explain what is wrong with the code?
Wrong syntax; an example based on Scott's schema:
SQL> select ename, sal from emp order by sal;
ENAME SAL
---------- ----------
SMITH 920
JAMES 950
ADAMS 1100
WARD 1250
MARTIN 1250
MILLER 1300
TURNER 1500 -- 8th --> you need this one
ALLEN 1600
CLARK 2450
BLAKE 2850
JONES 2975 -- ...
SCOTT 3000 -- 3rd
FORD 3000 -- 2nd
KING 10000 -- 1st, when sort is DESCending
14 rows selected.
SQL> with cte as
2 (select empno, ename, sal,
3 row_number() over (order by sal desc) rn
4 from emp
5 )
6 select empno, ename, sal
7 from cte
8 where rn = 8;
EMPNO ENAME SAL
---------- ---------- ----------
7844 TURNER 1500
SQL>