Oracle和MySQL中的分组（GROUP BY）后的聚合函数分别是什么？

在Oracle中，可以用WM_CONCAT函数或LISTAGG分析函数；在MySQL中可以使用GROUP_CONCAT函数。示例如下：

首先给出建表语句：

CREATE TABLE T_MAX_LHR (ARTICLE VARCHAR2(30),AUTHOR VARCHAR2(30),PRICE NUMBER); --Oracle

--CREATE TABLE T_MAX_LHR (ARTICLE VARCHAR(30),AUTHOR VARCHAR(30),PRICE FLOAT); --MySQL oracle通用

INSERT INTO T_MAX_LHR VALUES ('0001','B',3.99);

INSERT INTO T_MAX_LHR VALUES ('0002','A',10.99);

INSERT INTO T_MAX_LHR VALUES ('0003','C',1.69);

INSERT INTO T_MAX_LHR VALUES ('0004','B',19.95);

INSERT INTO T_MAX_LHR VALUES ('0005','A',6.96);

COMMIT;

SELECT * FROM T_MAX_LHR;

在MySQL中：

mysql> SELECT T.AUTHOR, GROUP_CONCAT(T.ARTICLE), GROUP_CONCAT(T.PRICE)

    ->   FROM T_MAX_LHR T

    ->  GROUP BY T.AUTHOR;

+--------+-------------------------+-----------------------+

| AUTHOR | GROUP_CONCAT(T.ARTICLE) | GROUP_CONCAT(T.PRICE) |

+--------+-------------------------+-----------------------+

| A      | 0002,0005               | 10.99,6.96            |

| B      | 0001,0004               | 3.99,19.95            |

| C      | 0003                    | 1.69                  |

+--------+-------------------------+-----------------------+

3 rows in set (0.00 sec)

在Oracle中：

LHR@orclasm >  SELECT T.AUTHOR, WM_CONCAT(T.ARTICLE) ARTICLE, WM_CONCAT(T.PRICE)  PRICE

  2    FROM T_MAX_LHR T

  3   GROUP BY T.AUTHOR;

AUTHOR   ARTICLE         PRICE

-------- --------------- ---------------

A        0002,0005       10.99,6.96

B        0001,0004       3.99,19.95

C        0003            1.69

LHR@orclasm >  SELECT T.AUTHOR,

  2          LISTAGG(T.ARTICLE, ',') WITHIN GROUP(ORDER BY T.PRICE) ARTICLE,

  3          LISTAGG(T.PRICE, ',') WITHIN GROUP(ORDER BY T.PRICE) PRICE

  4     FROM T_MAX_LHR T

  5    GROUP BY T.AUTHOR;

AUTHOR   ARTICLE         PRICE

-------- --------------- ---------------

A        0005,0002       6.96,10.99

B        0001,0004       3.99,19.95

C        0003            1.69