sql取每个分组的第一行数据

1 --建立测试环境 CREATE TABLE table1(a VARCHAR(10),b VARCHAR(10),c VARCHAR(10));

--插入数据 INSERT INTO table1 VALUES('2004','12','storea');

INSERT INTO table1 VALUES('2005','07','storea');

INSERT INTO table1 VALUES('2004','11','storeb');

INSERT INTO table1 VALUES('2005','06','storeb'); COMMIT;

2 取分组记录的第一条

解法一

SELECT a.* FROM table1 a INNER JOIN ( SELECT MAX(a + b)TIME FROM table1 GROUP BY c ) b ON a.a + a.b = b.TIME

解法二

SELECT * FROM scott.table1 a WHERE NOT EXISTS (SELECT 1 FROM scott.table1 b WHERE a.a=b.a AND TO_NUMBER(a.b)<TO_NUMBER(b.b));

解法三

SELECT * FROM (SELECT t.*, RANK() OVER (PARTITION BY t.a ORDER BY t.b DESC) AS drank FROM table1 t) a WHERE drank=1

引申

SELECT t.*,SUM(b) OVER (PARTITION BY t.a) AS aaa, SUM(b) OVER () AS bbb FROM table1 t ORDER BY t.a,t.b

－－－－－－

SELECT d.department_id , e.last_name, e.salary, RANK() OVER (PARTITION BY e.department_id ORDER BY e.salary) AS drank FROM employees e, departments d WHERE e.department_id = d.department_id AND d.department_id IN ('60', '90');