STD
Calculates the population standard deviation value from a set of numbers.
STD has synonyms STDDEV and STDDEV_POP which are equivalent.
May be used as a window function.
Syntax
STD returns NULL if there are not matching rows.
Aggregate Function
STD ( expression )
Window Function
STD (col | expr ) OVER ( [PARTITION BY (col | expr )] [ORDER BY (col | expr ) ] )
Arguments
expression: any expression. This may be a column name, the result of another function, or a math operation.
Return Type
A double.
Examples
CREATE TABLE player_scores(player_name VARCHAR(50), player_id VARCHAR(10),
1st_qtr_score DECIMAL(5,2), 2nd_qtr_score DECIMAL(5,2),
3rd_qtr_score DECIMAL(5,2), 4th_qtr_score DECIMAL(5,2),
yearly_total AS 1st_qtr_score + 2nd_qtr_score + 3rd_qtr_score + 4th_qtr_score PERSISTED DECIMAL(5,2));
INSERT INTO player_scores VALUES
('Steve', '119','22.50','72.00', '63.00', '45.00'),
('Jack', '432', '90.10', '78.00','88.20', '92.20'),
('Jim', '779','75.00', '68.90','55.70', '72.00'),
('Eve', '189','91.50', '88.10', '95.00', '94.50'),
('Shelia','338', '75.60', '72.00', '81.10', '78.40'),
('June', '521', '81.00', '87.30','76.80','82.20'),
('Martin', '674','98.80', '95.10', '88.00', '96.40');
Aggregate Function
SELECT STD(yearly_total) FROM player_scores; **** +-------------------+ | STD(yearly_total) | +-------------------+ | 57.083158 | +-------------------+
Window Function
SELECT player_name, yearly_total, ROUND(std(yearly_total) OVER (ORDER BY player_name, yearly_total)) as std FROM player_scores ORDER BY player_name; **** +-------------+--------------+------+ | player_name | yearly_total | std | +-------------+--------------+------+ | Eve | 369.10 | 0 | | Jack | 348.50 | 10 | | Jim | 271.60 | 42 | | June | 327.30 | 36 | | Martin | 378.30 | 38 | | Shelia | 307.10 | 37 | | Steve | 202.50 | 57 | +-------------+--------------+------+