CORR(expr1,expr2)

功能：计算两个变量的相关系数，作为聚集函数或分析函数。

示例：

返回staffS表中当月工资和经理编号的相关系数。

--删除表staffS。
DROP TABLE IF EXISTS staffS;
--创建表staffS。
CREATE TABLE  staffS
(
  staff_ID    NUMBER(6) not null,
  FIRST_NAME     VARCHAR2(20),
  LAST_NAME      VARCHAR2(25),
  EMAIL          VARCHAR2(25),
  PHONE_NUMBER   VARCHAR2(20),
  HIRE_DATE      DATE,
  employment_ID         VARCHAR2(10),
  SALARY         NUMBER(8,2),
  COMMISSION_PCT NUMBER(2,2),
  MANAGER_ID     NUMBER(6),
  section_ID  NUMBER(4)
);
--新增数据。
INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (198, 'Donald', 'OConnell', 'DOCONNEL', '650.507.9833', to_date('21-06-1999', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (199, 'Douglas', 'Grant', 'DGRANT', '650.507.9844', to_date('13-01-2000', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (200, 'Jennifer', 'Whalen', 'JWHALEN', '515.123.4444', to_date('17-09-1987', 'dd-mm-yyyy'), 'AD_ASST', 4400.00, null, 101, 10);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (198, 'Donald', 'OConnell', 'DOCONNEL', '650.507.9833', to_date('21-06-1999', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);
--查询工资与经理编号的相关系数。
SELECT CORR(SALARY,MANAGER_ID) FROM staffs;

CORR(SALARY,MANAGER_ID)
----------------------------------------
-1

1 rows fetched.

COUNT(expr)

CREATE TABLE  staffS
(
  staff_ID    NUMBER(6) not null,
  FIRST_NAME     VARCHAR2(20),
  LAST_NAME      VARCHAR2(25),
  EMAIL          VARCHAR2(25),
  PHONE_NUMBER   VARCHAR2(20),
  HIRE_DATE      DATE,
  employment_ID         VARCHAR2(10),
  SALARY         NUMBER(8,2),
  COMMISSION_PCT NUMBER(2,2),
  MANAGER_ID     NUMBER(6),
  section_ID  NUMBER(4)
);
INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (198, 'Donald', 'OConnell', 'DOCONNEL', '650.507.9833', to_date('21-06-1999', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (199, 'Douglas', 'Grant', 'DGRANT', '650.507.9844', to_date('13-01-2000', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (200, 'Jennifer', 'Whalen', 'JWHALEN', '515.123.4444', to_date('17-09-1987', 'dd-mm-yyyy'), 'AD_ASST', 4400.00, null, 101, 10);
SELECT COUNT(staff_ID) AS "COUNT" FROM staffS;

COUNT
--------------------
3

1 rows fetched.