CORR函数 看不明白

CORR聚集函数来计算相关系数

CORR：皮尔逊相关系数，是用于度量两个变量X和Y之间的相关（线性相关），其值介于-1与1之间。

CORR_S：斯皮尔曼等级相关

SELECT CORR(SYSDATE - hiredate, sal) AS corr_val,

       CORR_S(SYSDATE - hiredate, sal) AS corr_s_val,

       CORR_K(SYSDATE - hiredate, sal) AS corr_k_val

FROM emp;

SELECT deptno,

       CORR(SYSDATE - hiredate, sal) AS corr_val_by_job,

       CORR_S(SYSDATE - hiredate, sal) AS corr_s_val_by_job,

       CORR_K(SYSDATE - hiredate, sal) AS corr_k_val_by_job

FROM emp

GROUP BY deptno

ORDER BY deptno;

SELECT empno, ename, deptno,

sal, job,

       CORR(SYSDATE - hiredate, sal) OVER () AS corr_val

FROM   emp;

SELECT empno, ename, deptno,

sal, job,

       CORR(SYSDATE - hiredate, sal) OVER (PARTITION BY deptno) AS corr_val

FROM   emp;

SELECT empno, ename, deptno,

sal,job,

       CORR(SYSDATE - hiredate, sal) OVER (PARTITION BY job) AS corr_val

FROM   emp

ORDER BY JOB, deptno;