后浪云OceanBase教程：OceanBase MIN

​MIN​ 函数返回参数中指定列的最小值。

语法

MIN([ DISTINCT | UNIQUE | ALL ] expr) [ OVER (analytic_clause) ]

作为分析函数使用时，您需要使用窗口函数的完整语法，它对一组行的集合进行计算并返回多个值。作为聚合函数使用时，该函数对一组行的集合进行聚合计算，结果只能返回一个值，此时不需要加 ​OVER​ 关键字。

参数

返回类型

返回与 ​expr​ 相同数据类型的值。

示例

分析函数示例

以下语句创建了表 employees，并向里面插入数据：

CREATE TABLE employees (manager_id INT,last_name varchar(50),hiredate varchar(50),SALARY INT);
INSERT INTO employees VALUES(100, 'Raphaely', '2017-07-01', 1700);
INSERT INTO employees VALUES(100, 'De Haan', '2018-05-01',11000);      
INSERT INTO employees VALUES(100, 'Errazuriz', '2017-07-21', 1400);
INSERT INTO employees VALUES(100, 'Hartstein', '2019-05-01',14000);     
INSERT INTO employees VALUES(100, 'Raphaely', '2017-07-22', 1700);
INSERT INTO employees VALUES(100, 'Weiss',  '2019-07-11',13500);     
INSERT INTO employees VALUES(100, 'Russell', '2019-10-05', 13000);
INSERT INTO employees VALUES(100, 'Partners',  '2018-12-01',14000);     
INSERT INTO employees VALUES(200, 'Ross',  '2019-06-11',13500);     
INSERT INTO employees VALUES(200, 'Bell', '2019-05-25', 13000);
INSERT INTO employees VALUES(200, 'Part',  '2018-08-11',14000);

执行以下语句查询 SALARY 列的最小值：

SELECT manager_id, last_name, hiredate, salary, MIN(salary) OVER(PARTITION BY manager_id 
ORDER BY hiredate RANGE UNBOUNDED PRECEDING) AS p_cmin
FROM employees ORDER BY manager_id, last_name, hiredate, salary;
COMMIT;

查询结果如下：

+------------+-----------+------------+--------+--------+
| MANAGER_ID | LAST_NAME | HIREDATE   | SALARY | P_CMIN |
+------------+-----------+------------+--------+--------+
|        100 | De Haan   | 2018-05-01 |  11000 |   1400 |
|        100 | Errazuriz | 2017-07-21 |   1400 |   1400 |
|        100 | Hartstein | 2019-05-01 |  14000 |   1400 |
|        100 | Partners  | 2018-12-01 |  14000 |   1400 |
|        100 | Raphaely  | 2017-07-01 |   1700 |   1700 |
|        100 | Raphaely  | 2017-07-22 |   1700 |   1400 |
|        100 | Russell   | 2019-10-05 |  13000 |   1400 |
|        100 | Weiss     | 2019-07-11 |  13500 |   1400 |
|        200 | Bell      | 2019-05-25 |  13000 |  13000 |
|        200 | Part      | 2018-08-11 |  14000 |  14000 |
|        200 | Ross      | 2019-06-11 |  13500 |  13000 |
+------------+-----------+------------+--------+--------+

聚合函数示例

执行以下语句查询 SALARY 列的最小值：

SELECT MIN(salary)  FROM employees ;

查询结果如下：

+-------------+
| MIN(SALARY) |
+-------------+
|        1400 |
+-------------+