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Copy pathSQL windows functions
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279 lines (178 loc) · 4.08 KB
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Copy pathSQL windows functions
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279 lines (178 loc) · 4.08 KB
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use employees;
# ROW NUMBER
select emp_no,
salary,
row_number() over () AS ROW_NUM
from salaries
window w as (partition by emp_no order by salary desc);
select emp_no,
dept_no,
row_number() over (order by emp_no) as num_manager
from dept_manager;
select emp_no,
first_name,
last_name,
row_number() over (partition by first_name order by last_name ) AS ROW_NUm
from employees;
select emp_no,
salary,
-- row_number() over () AS ROW_NUM1,
row_number() over (partition by emp_no order by salary) AS ROW_NUM2,
row_number() over (partition by emp_no order by salary desc ) AS ROW_NUM3
-- row_number() over (order by salary desc) AS ROW_NUM4
from salaries;
SELECT
dm.emp_no,
s.salary,
ROW_NUMBER() OVER () AS row_num1,
ROW_NUMBER() OVER (PARTITION BY emp_no ORDER BY s.salary desc) AS row_num2
FROM
dept_manager dm
JOIN
salaries s ON dm.emp_no = s.emp_no
ORDER BY row_num1, emp_no, salary
;
SELECT
dm.emp_no,
s.salary,
ROW_NUMBER() OVER (PARTITION BY dm.emp_no ORDER BY s.salary ASC) AS row_num1,
ROW_NUMBER() OVER (PARTITION BY dm.emp_no ORDER BY s.salary DESC) AS row_num2
FROM
dept_manager dm
JOIN
salaries s ON dm.emp_no = s.emp_no
-- order by s.salary desC
;
select emp_no,
first_name,
row_number() over (partition by first_name order by emp_no) AS ROW_NUm
from employees
;
SELECT
emp_no,
first_name,
ROW_NUMBER() OVER w AS row_num
FROM
employees
WINDOW w AS (PARTITION BY emp_no ORDER BY emp_no);
select a.emp_no,
min(a.salary) from
(select emp_no,
salary,
row_number() over (partition by emp_no order by salary desc) AS ROW_NUM
from salaries) a
where ROW_NUM = 2;
select w.emp_no,
min(w.salary) from (select emp_no,salary,
row_number() over (partition by emp_no order by salary) AS ROW_NUM
from salaries) w
group by emp_no;
SELECT a.emp_no,
MIN(salary) AS min_salary FROM (
SELECT
emp_no, salary, ROW_NUMBER() OVER w AS row_num
FROM
salaries
WINDOW w AS (PARTITION BY emp_no ORDER BY salary)) a
GROUP BY emp_no;
-- Solution #2:
SELECT a.emp_no,
MIN(salary) AS min_salary FROM (
SELECT
emp_no, salary, ROW_NUMBER() OVER (PARTITION BY emp_no ORDER BY salary) AS row_num
FROM
salaries) a
GROUP BY emp_no;
-- Solution #3:
SELECT
emp_no, MIN(salary) AS min_salary
FROM
(SELECT
emp_no, salary
FROM
salaries) a
GROUP BY emp_no;
-- Solution #4:
SELECT a.emp_no,
a.salary as min_salary
FROM (
SELECT
emp_no, salary, ROW_NUMBER() OVER w AS row_num
FROM
salaries
WINDOW w AS (PARTITION BY emp_no ORDER BY salary)) a
WHERE row_num=1;
-- Solution #5:
SELECT a.emp_no,
a.salary as min_salary FROM (
SELECT
emp_no, salary, ROW_NUMBER() OVER w AS row_num
FROM
salaries
WINDOW w AS (PARTITION BY emp_no ORDER BY salary)) a
WHERE a.row_num=2;
-- --------------------------------
select
emp_no, salary,
row_number() over (partition by emp_no order by salary desc) AS ROW_NUM
from salaries
where emp_no = 11839
;
-- RANK() and DENSE_RANK()
select
emp_no,
(count(SALARY) - count(distinct salary)) AS DIFF
from salaries
group by emp_no
having DIFF > 0
ORDER BY emp_no
;
select
emp_no, salary,
rank() over (partition by emp_no order by salary desc) AS RANK_NUM
from salaries
where emp_no = 11839;
select
emp_no, salary,
dense_rank() over (partition by emp_no order by salary desc) AS RANK_NUM
from salaries
where emp_no = 11839;
select
emp_no, salary,
rank() over (partition by emp_no order by salary ) AS RANK_NUM;
-- Solution #1:
SELECT
emp_no,
salary,
ROW_NUMBER() OVER w AS row_num
FROM
salaries
WHERE emp_no = 10560
WINDOW w AS (PARTITION BY emp_no ORDER BY salary DESC);
-- Solution #2:
SELECT
dm.emp_no, (COUNT(salary)) AS no_of_salary_contracts
FROM
dept_manager dm
JOIN
salaries s ON dm.emp_no = s.emp_no
GROUP BY emp_no
ORDER BY emp_no;
-- Solution #3:
SELECT
emp_no,
salary,
RANK() OVER w AS rank_num
FROM
salaries
WHERE emp_no = 10560
WINDOW w AS (PARTITION BY emp_no ORDER BY salary DESC);
-- Solution #4:
SELECT
emp_no,
salary,
DENSE_RANK() OVER w AS rank_num
FROM
salaries
WHERE emp_no = 10560
WINDOW w AS (PARTITION BY emp_no ORDER BY salary DESC);