MYSQL-实现ORACLE- row_number() over(partition by ) 分组排序功能
由于MYSQL没有提供类似ORACLE中OVER()这样丰富的分析函数. 所以在MYSQL里需要实现这样的功能,我们只能用一些灵活的办法:
1.首先我们来创建实例数据:
drop table if exists heyf_t10;
create table heyf_t10 (empid int ,deptid int ,salary decimal(10,2) );
insert into heyf_t10 values
(1,10,5500.00),
(2,10,4500.00),
(3,20,1900.00),
(4,20,4800.00),
(5,40,6500.00),
(6,40,14500.00),
(7,40,44500.00),
(8,50,6500.00),
(9,50,7500.00);2. 确定需求: 根据部门来分组,显示各员工在部门里按薪水排名名次.
显示结果预期如下:
+-------+--------+----------+------+
| empid | deptid | salary | rank |
+-------+--------+----------+------+
| 1 | 10 | 5500.00 | 1 |
| 2 | 10 | 4500.00 | 2 |
| 4 | 20 | 4800.00 | 1 |
| 3 | 20 | 1900.00 | 2 |
| 7 | 40 | 44500.00 | 1 |
| 6 | 40 | 14500.00 | 2 |
| 5 | 40 | 6500.00 | 3 |
| 9 | 50 | 7500.00 | 1 |
| 8 | 50 | 6500.00 | 2 |
+-------+--------+----------+------+
9 rows in set (0.00 sec)3. SQL 实现
SELECT
empid,
deptid,
salary,
rank
FROM
(
SELECT
empid,
deptid,
salary,
IF (
@pdept = src.deptid ,@rank := @rank + 1 ,@rank := 1
) AS rank,
@pdept := src.deptid AS g
FROM
(
SELECT
empid,
deptid,
salary
FROM
heyf_t10
ORDER BY
deptid ASC,
salary DESC
) src,
(
SELECT
@pdept := NULL ,@rank := 0
) var
) z;4. 结果演示
mysql> SELECT
-> empid,
-> deptid,
-> salary,
-> rank
-> FROM
-> (
-> SELECT
-> empid,
-> deptid,
-> salary,
->
-> IF (
-> @pdept = src.deptid ,@rank := @rank + 1 ,@rank := 1
-> ) AS rank,
-> @pdept := src.deptid AS g
-> FROM
-> (
-> SELECT
-> empid,
-> deptid,
-> salary
-> FROM
-> heyf_t10
-> ORDER BY
-> deptid ASC,
-> salary DESC
-> ) src,
-> (
-> SELECT
-> @pdept := NULL ,@rank := 0
-> ) var
-> ) z;
+-------+--------+----------+------+
| empid | deptid | salary | rank |
+-------+--------+----------+------+
| 1 | 10 | 5500.00 | 1 |
| 2 | 10 | 4500.00 | 2 |
| 4 | 20 | 4800.00 | 1 |
| 3 | 20 | 1900.00 | 2 |
| 7 | 40 | 44500.00 | 1 |
| 6 | 40 | 14500.00 | 2 |
| 5 | 40 | 6500.00 | 3 |
| 9 | 50 | 7500.00 | 1 |
| 8 | 50 | 6500.00 | 2 |
+-------+--------+----------+------+
9 rows in set (0.00 sec)
我的SQL:
SELECT
MESSAGE_ID,
GET_USER_ID,
SEND_USER_ID,
MESSAGE_CONTEXT,
CREATE_TIME
FROM
(
SELECT
SRC.*,
IF (
@V_USER_ID = USER_ID ,@V_RANK := @V_RANK + 1 ,@V_RANK := 1
) AS RANK ,@V_USER_ID := USER_ID AS G_USER_ID
FROM
(
SELECT
MESSAGE_ID,
USER_ID,
CREATE_TIME,
MESSAGE_CONTEXT,
GET_USER_ID,
SEND_USER_ID
FROM
(
SELECT
MESSAGE_ID,
GET_USER_ID,
SEND_USER_ID,
GET_USER_ID AS USER_ID,
CREATE_TIME,
MESSAGE_CONTEXT
FROM
T_SD_MESSAGE
WHERE
GET_USER_ID != '1234'
UNION ALL
SELECT
MESSAGE_ID,
GET_USER_ID,
SEND_USER_ID,
SEND_USER_ID AS USER_ID,
CREATE_TIME,
MESSAGE_CONTEXT
FROM
T_SD_MESSAGE
WHERE
SEND_USER_ID != '1234'
) METADATA
ORDER BY
USER_ID ASC,
CREATE_TIME DESC
) SRC,
(
SELECT
@V_RANK = 0,
@V_USER_ID := NULL
) VARS
) SRC
WHERE
RANK = 1
ORDER BY
CREATE_TIME DESC一个过程;
DROP PROCEDURE
IF EXISTS PROCE_USER_NEW_MSG;
DROP TEMPORARY TABLE
IF EXISTS TEM_USER_NEW_MSG;
DELIMITER ||
CREATE PROCEDURE PROCE_USER_NEW_MSG (
IN FRIST_RESULT INT,
IN FETCH_SIZE INT
)
BEGIN
SELECT
M.MESSAGE_ID,
M.GET_USER_ID,
M.SEND_USER_ID,
M.MESSAGE_CONTEXT,
M.CREATE_TIME,
G_U.USER_NAME AS G_USER_NAME,
S_U.USER_NAME AS S_USER_NAME,
G_H.GENERAL_PIC_THUMBNAIL_URL AS G_HEADER,
S_H.GENERAL_PIC_THUMBNAIL_URL AS S_HEADER
FROM
T_SD_MESSAGE M
LEFT JOIN T_SD_USER G_U ON M.GET_USER_ID = G_U.USER_ID
LEFT JOIN T_SD_USER S_U ON M.SEND_USER_ID = S_U.USER_ID
LEFT JOIN T_SD_GENERAL_PICTURE G_H ON G_H.GENERAL_PICTURE_ID = G_U.USER_HEADER_PIC_ID
LEFT JOIN T_SD_GENERAL_PICTURE S_H ON S_H.GENERAL_PICTURE_ID = S_U.USER_HEADER_PIC_ID
WHERE
M.MESSAGE_ID IN (
SELECT
MESSAGE_ID
FROM
(
SELECT
MESSAGE_ID,
RANK,
MESSAGE_CONTEXT,
CREATE_TIME
FROM
(
SELECT
SRC.*,
IF (
@V_USER_ID = USER_ID ,@V_RANK := @V_RANK + 1 ,@V_RANK := 1
) AS RANK ,@V_USER_ID := USER_ID AS G_USER_ID
FROM
(
SELECT
MESSAGE_ID,
USER_ID,
CREATE_TIME,
MESSAGE_CONTEXT,
GET_USER_ID,
SEND_USER_ID
FROM
(
SELECT
MESSAGE_ID,
GET_USER_ID,
SEND_USER_ID,
GET_USER_ID AS USER_ID,
CREATE_TIME,
MESSAGE_CONTEXT
FROM
T_SD_MESSAGE
WHERE
GET_USER_ID != '3000'
UNION ALL
SELECT
MESSAGE_ID,
GET_USER_ID,
SEND_USER_ID,
SEND_USER_ID AS USER_ID,
CREATE_TIME,
MESSAGE_CONTEXT
FROM
T_SD_MESSAGE
WHERE
SEND_USER_ID != '3000'
) METADATA
ORDER BY
USER_ID ASC,
CREATE_TIME DESC
) SRC,
(
SELECT
@V_RANK = 0,
@V_USER_ID := NULL
) VARS
) SRC
WHERE
RANK = 1
ORDER BY
CREATE_TIME DESC
) SRC
)
ORDER BY
M.CREATE_TIME DESC
LIMIT FRIST_RESULT,
FETCH_SIZE ;
END||
DELIMITER ;
-- LIMIT FRIST_RESULT ,FETCH_SIZE
CALL PROCE_USER_NEW_MSG (0, 2);
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