NEW analytical Function in SQL

COVAR_POP

Returns the population covariance of  a set of number pairs COVAR_POP(<expression1>, <expression2>) OVER (<analytic clause>)
conn oe/oe

SELECT job_id,
COVAR_POP(SYSDATE-hire_date, salary) AS covar_pop,
COVAR_SAMP(SYSDATE-hire_date, salary) AS covar_samp
FROM employees
WHERE department_id in (50, 80)
GROUP BY job_id; 
 

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COVAR_SAMP
Returns the sample covariance of a set of number pairs COVAR_SAMP(<expression1>, <expression2>) OVER (<analytic clause>)
See COVAR_POP Demo above 
 

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CUME_DIST

Returns the cumulative distribution of a value in a group of values CUME_DIST(<value>) OVER (<partition_clause> <order by clause>)
conn oe/oe

SELECT job_id, last_name, salary, CUME_DIST()
OVER (PARTITION BY job_id ORDER BY salary) AS cume_dist
FROM employees
WHERE job_id LIKE 'PU%'; 
 

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DENSE_RANK

Ranks items in a group leaving no gaps in ranking sequence when there are ties DENSE_RANK() OVER (<query_partition_clause> <order_by_clause>)
conn oe/oe

SELECT d.department_name, e.last_name, e.salary, DENSE_RANK()
OVER (PARTITION BY e.department_id ORDER BY e.salary) AS DENSE_RANK
FROM employees e, departments d
WHERE e.department_id = d.department_id
AND d.department_id IN (30, 60); 
 

************************************************************************


FIRST

Returns the row ranked first using DENSE_RANK SELECT <aggregate_function(column_name)> KEEP
(DENSE_RANK FIRST ORDER BY <column_name> [<ASC|DESC> NULLS <FIRST|LAST>)
OVER (PARTITION BY <column_name>)
FROM <table_name>
GROUP BY <column_name>;
conn oe/oe

SELECT last_name, department_id, salary,
MIN(salary) KEEP (DENSE_RANK FIRST ORDER BY commission_pct)
OVER (PARTITION BY department_id) "Worst",
MAX(salary) KEEP (DENSE_RANK LAST ORDER BY commission_pct)
OVER (PARTITION BY department_id) "Best"
FROM employees
WHERE department_id IN (30, 60)
ORDER BY department_id, salary;

************************************************************************


FIRST_VALUE

Returns the first value in an ordered set of values. If the first value in the set is null, then the function returns NULL unless you specify IGNORE NULLS FIRST_VALUE(<expression> [IGNORE NULLS])
OVER (<analytic clause>)

conn oe/oe

SELECT last_name, salary, hire_date, FIRST_VALUE(hire_date)
OVER (ORDER BY salary ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS lv
FROM (SELECT * FROM employees WHERE department_id = 90
ORDER BY hire_date);

 
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IGNORE NULLS

The following is a minor modification of a demo published in the November/December 2006 issue of Oracle Magazine by Tom Kyte (<column_name> IGNORE NULLS)

CREATE TABLE t1 (
row_num NUMBER(3),
col1 VARCHAR2(15),
col2 VARCHAR2(15));

INSERT INTO t1 VALUES (6, NULL, NULL);
INSERT INTO t1 VALUES (1, 'Category 1', 'Mango');
INSERT INTO t1 VALUES (2, NULL, NULL);
INSERT INTO t1 VALUES (3, NULL, NULL);
INSERT INTO t1 VALUES (4, NULL, 'Banana');
INSERT INTO t1 VALUES (5, NULL, NULL);
INSERT INTO t1 VALUES (6, NULL, NULL);
INSERT INTO t1 VALUES (7, 'Category 2', 'Vanilla');
INSERT INTO t1 VALUES (8, NULL, NULL);
INSERT INTO t1 VALUES (9, 'Category 3', 'Strawberry');
COMMIT;

SELECT * FROM t1;

SELECT row_num,
LAST_VALUE(col1 IGNORE NULLS) OVER (ORDER BY row_num) col1,
LAST_VALUE(col2 IGNORE NULLS) OVER (ORDER BY row_num) col2
FROM t1
ORDER BY row_num;

************************************************************************

LAG
LAG provides access to more than one row of a table at the same time without a self-join. Given a series of rows returned from a query and a position of the cursor, LAG provides access to a row at a given physical offset prior to that position. LAG(<value expression>, <offset>, <default>)
OVER ([<query partition clause>] <order_by_clause>)
conn oe/oe

SELECT last_name, hire_date, salary,
LAG(salary, 1, 0) OVER (ORDER BY hire_date) AS PREV_SAL
FROM employees
WHERE job_id = 'PU_CLERK'; 
 

************************************************************************

 
LAST
Returns the row ranked last using DENSE_RANK <aggregate function> KEEP (DENSE_RANK LAST ORDER BY
(<expression> <ASC | DESC> NULLS <FIRST | LAST>)
See FIRST Demo above 
 


************************************************************************

LAST_VALUE
Returns the last value in an ordered set of values. If the last value in the set is null, then the function returns NULL unless you specify IGNORE NULLS. This setting is useful for data densification. If you specify IGNORE NULLS, then LAST_VALUE returns the first non-null value in the set, or NULL if all values are null. LAST_VALUE (<expression> IGNORE NULLS) OVER (<analytic clause>)
conn oe/oe

SELECT last_name, salary, hire_date, FIRST_VALUE(hire_date)
OVER (ORDER BY salary ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS lv
FROM (SELECT * FROM employees WHERE department_id = 90
ORDER BY hire_date); 
 

************************************************************************
 
LEAD

LEAD provides access to a row at a given physical offset beyond that position LEAD(<expression, offset, default>)
[(<query_partition_clause>)]
OVER (<order_by_clause>)
SELECT submit_date, num_votes,
LEAD(num_votes, 1, 0) OVER (ORDER BY submit_date) AS NEXT_VAL
FROM vote_count; 
 

************************************************************************


MAX

Returns the maximum value by partition MAX (<DISTINCT | ALL> expression) OVER (<analytic clause>)
conn oe/oe

SELECT manager_id, last_name, salary
FROM (
  SELECT manager_id, last_name, salary,
  MAX(salary) OVER (PARTITION BY manager_id) AS rmax_sal
  FROM employees)
WHERE salary = rmax_sal; 
 

************************************************************************

 
MIN

Returns the minimum value by partition MIN (<DISTINCT | ALL> expression) OVER (<analytic clause>)
conn oe/oe

SELECT manager_id, last_name, salary
FROM (
  SELECT manager_id, last_name, salary,
  MAX(salary) OVER (PARTITION BY manager_id) AS rmax_sal
  FROM employees)
WHERE salary = rmax_sal; 
 

************************************************************************

 
NTILE
Divides an ordered data set into a number of buckets indicated by expr and assigns the appropriate bucket number to each row. The buckets are numbered 1 through expr. The expr value must resolve to a positive constant for each partition. NTILE (<expression>) OVER ([query_partition_clause] <order by clause>)
conn oe/oe

SELECT last_name, salary,
NTILE(4) OVER (ORDER BY salary DESC) AS quartile
FROM employees
WHERE department_id = 100; 
 

************************************************************************


OVER PARTITION BY

This demo returns employees that
are making above average salary in their respective department NTILE (<expression>) OVER ([query_partition_clause] <order by clause>)
conn hr/hr

col ename format a30
col department_name format a20

SELECT * FROM (
  SELECT e.ffirst_name || ' ' || e.last_name ENAME, d.department_name,
  e.salary, TRUNC(e.salary - avg(e.salary) OVER (PARTITION BY
  e.department_id)) sal_dif
FROM employees e, departments d
WHERE e.department_id=d.department_id)
WHERE sal_dif > 0
ORDER BY 2,4 DESC; 
 

************************************************************************

 
PERCENT_RANK
For a row r, PERCENT_RANK calculates the rank of r minus 1, divided by 1 less than the number of rows being evaluated (the entire query result set or a partition). PERCENT_RANK(<value>) OVER (<partition_clause> <order_by_clause>)
conn oe/oe

SELECT department_id, last_name, salary, PERCENT_RANK()
OVER (PARTITION BY department_id ORDER BY salary DESC) AS pr
FROM employees
ORDER BY pr, salary; 
 

************************************************************************


PERCENTILE_CONT
Inverse distribution function that assumes a continuous distribution model. It takes a percentile value and a sort specification, and returns an interpolated value that would fall into that percentile value with respect to the sort specification. Nulls are ignored in the calculation. PERCENTILE_CONT(<value>) WITHIN GROUP (ORDER BY <expression> [ASC | DESC]) OVER (<partition_clause>)
conn oe/oe

SELECT last_name, salary, department_id,
PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY salary DESC)
OVER (PARTITION BY department_id) PCT_CONT, PERCENT_RANK()
OVER (PARTITION BY department_id ORDER BY salary DESC) PCT_RANK
FROM employees
WHERE department_id IN (30, 60); 

************************************************************************

 
PERCENTILE_DISC
An inverse distribution function that assumes a discrete distribution model. It takes a percentile value and a sort specification and returns an element from the set. Nulls are ignored in the calculation. PERCENTILE_DISC(<expression>) WITHIN GROUP (ORDER BY <order_by_clause>)
conn oe/oe

col cume_dist format 9.999

SELECT last_name, salary, department_id,
PERCENTILE_DISC(0.5) WITHIN GROUP (ORDER BY salary DESC)
OVER (PARTITION BY department_id) PCT_DISC,
CUME_DIST() OVER (PARTITION BY department_id
ORDER BY salary DESC) CUME_DIST
FROM employees
WHERE department_id IN (30, 60); 
 

************************************************************************

 
RANK

Calculates the rank of a value in a group of values RANK(<value>) OVER (<partition_clause> ORDER BY <order_by_clause>)
conn oe/oe

SELECT department_id, last_name, salary, commission_pct,
RANK() OVER (PARTITION BY department_id
ORDER BY salary DESC, commission_pct) "Rank"
FROM employees
WHERE department_id = 80;

/* The following query finds the 5 top-selling products for each product subcategory where that product contributes more than 20% of the sales within its product category. */
conn sh/sh

col categ format a15
col prod_subcategory format a20

SELECT SUBSTR(prod_category,1,8) AS CATEG, prod_subcategory, prod_id, sales
FROM (
  SELECT p.prod_category, p.prod_subcategory, p.prod_id,
  SUM(amount_sold) as SALES, SUM(SUM(amount_sold))
  OVER (PARTITION BY p.prod_category) AS CAT_SALES,
  SUM(SUM(amount_sold))
  OVER (PARTITION BY p.prod_subcategory) AS SUBCAT_SALES,
  RANK() OVER (PARTITION BY p.prod_subcategory
  ORDER BY SUM(amount_sold) ) AS RANK_IN_LINE
  FROM sales s, customers c, countries co, products p
  WHERE s.cust_id = c.cust_id
  AND c.country_id = co.country_id
  AND s.prod_id = p.prod_id
  AND s.time_id = TO_DATE('11-OCT-2000')
  GROUP BY p.prod_category, p.prod_subcategory, p.prod_id
  ORDER BY prod_category, prod_subcategory)
WHERE SUBCAT_SALES > 0.2 * CAT_SALES
AND RANK_IN_LINE<=5; 
 

************************************************************************

 
RATIO_TO_REPORT
Computes the ratio of a value to the sum of a set of values. If expr evaluates to null, then the ratio-to-report value also evaluates to null. RATIO_TO_REPORT(<value>) OVER (<partition_clause>)
conn oe/oe

SELECT last_name, salary, RATIO_TO_REPORT(salary) OVER () AS RR
FROM employees
WHERE job_id = 'PU_CLERK'; 
 

************************************************************************


REGR_ (Linear Regression) Functions
Generic Syntax FUNCTION_NAME (<expression1>,<expression2>) OVER (<analytic_clause>)

REGR_AVGX -- see REGR_AVGX Demo

conn oe/oe
SELECT job_id, employee_id ID, salary,
REGR_SLOPE(SYSDATE-hire_date, salary)
OVER (PARTITION BY job_id) slope,
REGR_INTERCEPT(SYSDATE-hire_date, salary)
OVER (PARTITION BY job_id) intcpt,
REGR_R2(SYSDATE-hire_date, salary)
OVER (PARTITION BY job_id) rsqr,
REGR_COUNT(SYSDATE-hire_date, salary)
OVER (PARTITION BY job_id) count,
REGR_AVGX(SYSDATE-hire_date, salary)
OVER (PARTITION BY job_id) avgx,
REGR_AVGY(SYSDATE-hire_date, salary)
OVER (PARTITION BY job_id) avgy
FROM employees
WHERE department_id in (50, 80)
ORDER BY job_id, employee_id;

REGR_AVGY -- see REGR_AVGX Demo

conn oe/oe

SELECT job_id,
REGR_AVGY(SYSDATE - hire_date, salary) avgy,
REGR_AVGX(SYSDATE - hire_date, salary) avgx
FROM employees
WHERE department_id in (30, 50)
GROUP BY job_id;

REGR_COUNT -- see REGR_AVGX Demo

conn oe/oe

SELECT job_id,
REGR_COUNT(SYSDATE-hire_date, salary) count
FROM employees
WHERE department_id in (30, 50)
GROUP BY job_id;

REGR_INTERCEPT -- see REGR_AVGX Demo

conn oe/oe

SELECT job_id,
REGR_SLOPE(SYSDATE - hire_date, salary) slope,
REGR_INTERCEPT(SYSDATE - hire_date, salary) intercept
FROM employees
WHERE department_id in (50,80)
GROUP BY job_id
ORDER BY job_id;

REGR_R2 -- see REGR_AVGX Demo

conn oe/oe

SELECT job_id, REGR_R2(SYSDATE-hire_date, salary) Regr_R2
FROM employees
WHERE department_id IN (50, 80)
GROUP by job_id;
REGR_SLOPE See REGR_AVGX Demo
See REGR_INTERCEPT Demo

REGR_SXX conn oe/oe

SELECT job_id,
REGR_SXY(SYSDATE - hire_date, salary) regr_sxy,
REGR_SXX(SYSDATE - hire_date, salary) regr_sxx,
REGR_SYY(SYSDATE - hire_date, salary) regr_syy
FROM employees
WHERE department_id in (50, 80)
GROUP BY job_id
ORDER BY job_id;
REGR_SXY See REGR_SXX Demo
REGR_SYY See REGR_SXX Demo 
 


************************************************************************

ROW_NUMBER

Assigns a unique number to each row to which it is applied (either each row in the partition or each row returned by the query), in the ordered sequence of rows specified in the order by clause, beginning with 1. ROW_NUMBER(<value>) OVER (<partition_clause> ORDER BY <order_by_clause>)
CREATE TABLE test (
id      NUMBER(1),
degrees NUMBER(3));

INSERT INTO test VALUES (0,235);
INSERT INTO test VALUES (0,276);
INSERT INTO test VALUES (1,211);
INSERT INTO test VALUES (1,250);
INSERT INTO test VALUES (1,255);
INSERT INTO test VALUES (2,55);
INSERT INTO test VALUES (2,277);
INSERT INTO test VALUES (2,69);
INSERT INTO test VALUES (3,25);
INSERT INTO test VALUES (3,166);
INSERT INTO test VALUES (3,262);
INSERT INTO test VALUES (4,47);
INSERT INTO test VALUES (4,238);
INSERT INTO test VALUES (4,40);
COMMIT;

SELECT * FROM test;

-- choose the starting cell
SELECT id, degrees s
FROM (
  SELECT id, degrees, (360 - degrees) d360,
  ROW_NUMBER() OVER(PARTITION BY id
  ORDER BY CASE
    WHEN (degrees < 360 - degrees) THEN degrees
    ELSE 360 - degrees
    END) rn
  FROM test) t
WHERE rn = 1;

-- order the rest clockwise
SELECT *
FROM (
  SELECT t.id, t.degrees,
  ROW_NUMBER() OVER(PARTITION BY t.id
  ORDER BY CASE
    WHEN (t.degrees < starting_cell.degrees) THEN t.degrees + 360
    ELSE t.degrees
    END) rn
  FROM test t
JOIN (
  SELECT id, degrees, (360 - degrees) d360,
  ROW_NUMBER() OVER(PARTITION BY id
  ORDER BY CASE
    WHEN (degrees < 360 - degrees) THEN degrees
    ELSE 360 - degrees
    END) rn
  FROM test) starting_cell
  ON t.id = starting_cell.id
  WHERE starting_cell.rn=1)t
ORDER BY id, rn; 
 

************************************************************************

 
STDDEV

Returns the sample standard deviation of an expression STDDEV([DISTINCT | ALL] <expression>) OVER (<analytic_clause>)
conn oe/oe

col stddev format 99999.999

SELECT last_name, salary,
STDDEV(salary) OVER (ORDER BY hire_date) "StdDev"
FROM employees
WHERE department_id = 30; 
 

************************************************************************


STDDEV_POP
Computes the population standard deviation and returns the square root of the population variance STDDEV_POP(<expression>) OVER (<analytic_clause>)
conn oe/oe

SELECT department_id, last_name, salary,
STDDEV_POP(salary) OVER (PARTITION BY department_id) AS pop_std
FROM employees; 
 

************************************************************************


 
STDDEV_SAMP

Computes the cumulative sample standard deviation and returns the square root of the sample variance. STDDEV_SAMP(<expression>) OVER (<analytic_clause>)
conn oe/oe

SELECT department_id, last_name, hire_date, salary,
STDDEV_SAMP(salary) OVER (PARTITION BY department_id
ORDER BY hire_date
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS cum_sdev
FROM employees; 
 

************************************************************************


SUM

Computes the cumulative sample running sum
Corrected thanks to a note from Mette Stephansen in Denmark.  
CREATE TABLE vote_count (
submit_date  DATE NOT NULL,
num_votes    NUMBER NOT NULL);

INSERT INTO vote_count VALUES (TRUNC(SYSDATE)-4, 100);
INSERT INTO vote_count VALUES (TRUNC(SYSDATE)-3, 150);
INSERT INTO vote_count VALUES (TRUNC(SYSDATE)-2, 75);
INSERT INTO vote_count VALUES (TRUNC(SYSDATE)-3, 25);
INSERT INTO vote_count VALUES (TRUNC(SYSDATE)-1, 50);
COMMIT;

SELECT * FROM vote_count;

SELECT submit_date, num_votes, SUM(num_votes)
OVER(ORDER BY submit_date ROWS UNBOUNDED PRECEDING) TOT_VOTE
FROM vote_count
ORDER BY submit_date; 
 

************************************************************************

 
VAR_POP

Returns the population variance of a set of numbers VAR_POP(<value>) OVER (<analytic_clause>)
conn sh/sh

SELECT t.calendar_month_desc, VAR_POP(SUM(s.amount_sold))
OVER (ORDER BY t.calendar_month_desc) "Var_Pop",
VAR_SAMP(SUM(s.amount_sold))
OVER (ORDER BY t.calendar_month_desc) "Var_Samp"
FROM sales s, times t
WHERE s.time_id = t.time_id AND t.calendar_year = 2001
GROUP BY t.calendar_month_desc; 
 

************************************************************************

 
VAR_SAMP
Returns the sample variance of a set of numbers VAR_SAMP(<value>) OVER (<analytic_clause>)
See VAR_POP Demo above 
 

************************************************************************
 
VARIANCE

Returns the variance of an expression VARIANCE([DISTINCT | ALL] <value>) OVER (<analytic_clause>)
conn oe/oe

SELECT last_name, salary,
VARIANCE(salary) OVER (ORDER BY hire_date) AS VARIANCE
FROM employees
WHERE department_id = 30; 
************************************************************************

 
Additional Demos
Another example:

This one written by Maxim Demenko CREATE TABLE test (id, quality, weight) AS
SELECT 1,'A',10 FROM dual UNION ALL
SELECT 2,'A',11 FROM dual UNION ALL
SELECT 3,'A',12 FROM dual UNION ALL
SELECT 4,'B',11 FROM dual UNION ALL
SELECT 5,'B',19 FROM dual UNION ALL
SELECT 6,'A',9 FROM dual UNION ALL
SELECT 7,'A',14 FROM dual UNION ALL
SELECT 8,'C',4 FROM dual UNION ALL
SELECT 9,'C',7 FROM dual;

SELECT *
FROM test;

SELECT MAX(id) ID, MAX(quality) QUALITY, SUM(weight) WEIGHT
FROM (
  SELECT id, quality, weight, SUM(new_seq) OVER (ORDER BY id) new_grp
  FROM (
    SELECT id, quality, weight, DECODE(LAG(quality) OVER (ORDER BY id),
    quality, 0, id) new_seq
FROM test))
GROUP BY new_grp
ORDER BY 1;