COVAR,COVAR_POP

Description

Calculate the covariance between two numeric variables.

Alias

• COVAR_POP

Syntax

COVAR(<expr1>, <expr2>)

Parameters

Parameter	Description
<expr1>	Numeric expression or column
<expr2>	Numeric expression or column

Return Value

Returns the covariance value of expr1 and expr2, special case:

• If a column of expr1 or expr2 is NULL, the row data will not be counted in the final result.

Example

-- setup
create table baseall(
    id int,
    x double,
    y double
) distributed by hash(id) buckets 1
properties ("replication_num"="1");

insert into baseall values
    (1, 1.0, 2.0),
    (2, 2.0, 3.0),
    (3, 3.0, 4.0),
    (4, 4.0, NULL),
    (5, NULL, 5.0);

select covar(x,y) from baseall;

+---------------------+
| covar(x, y)          |
+---------------------+
| 0.89442719099991586 |
+---------------------+