2. dense_rank()和rank over()很像,但学生成绩并列后并不会空出并列所占的名次,如下1 2 2 3 4 select name, course, dense_rank() over(partition by course order by score desc) as rank from student; 3. row_number这个函数不需要考虑是否并列,那怕根据条件查询出来的数值相同也会进行连续排名 selec...
c:770 #8 0x0000000000749bc6 in exec_simple_query (query_string=0x1becfa0 "select row_number() over() as rownum, id from aa;") at postgres.c:1231 #9 0x000000000074aea2 in PostgresMain (argc=<optimized out>, argv=argv@entry=0x1c16f70, dbname=0x1c16e98 "postgres", username=<...
select e1.*,e2.ename 上级姓名 from emp e1 join emp e2 on e1.mgr=e2.empno 不等连接:连接条件是不等条件,(大于、小于、不等于) select e.*,s.grade,s.losal,s.hisal from emp e join salgrade s on e.sal between s.losal and s.hisal; 全连接:它会查出两个表中的所有数据 select 列名,列...
The reason is that the ROW_NUMBER() operates on the result set before the DISTINCT is applied. To solve this problem, we can get a list of distinct prices in a CTE, then apply the ROW_NUMBER() function in the outer query as follows: WITH prices AS ( SELECT DISTINCT price FROM ...
rownum在select列表中时重写为row_number() over ()rownum在where子句中时重写为limit... offset... 虚拟列rowid Oracle中的rowid虚拟列返回特定行的具体地址,在PostgreSQL中重写为tableoid || '#' || ctid。 字符串函数 nvl(col, value) Oracle中的nvl(col, value)用来设置默认值,col为空就设置为value;在...
SELECT ROW_NUMBER () OVER ( ORDER BY starttime DESC ) "id", starttime AS "text", starttime FROM warning_products WHERE pid_model = '结果' AND starttime IS NOT NULL GROUP BY starttime 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. ...
SELECTd.department_name"部门名称",concat(e.first_name,',',e.last_name)"姓名",e.salary"月薪",ROW_NUMBER()OVER(PARTITIONBYe.department_idORDERBYe.salaryDESC)AS"row_number",RANK()OVER(PARTITIONBYe.department_idORDERBYe.salaryDESC)AS"rank",DENSE_RANK()OVER(PARTITIONBYe.department_idORDERBYe....
一、查询基础 1、连接数据库 C:\PostgreSQL\9.5\bin\psql.exe -U postgres -d shop 2、检查数据库连接是否成功 SELECT 1; 3、创建数据库 CREATE DATABASE shop; 4、退出数据库口令 \q 5、\d 数据库 ——得到所有表的
row_number函数 2、rank函数 rank的官方解释是:带间隙的当前行排名; 与该行的第一个同等行的row_number相同 select country_name,"year",gdp,rank() over(order by "year" desc) from country_gdp_year_final where country_code in('CHN','JPN','USA','DEU','CAN','FRA'); ...
先利用row_number()提取每个轨迹点在该车辆的行驶轨迹中的位置序列(简单理解为依据时间递增排序的行号),之后利用array_agg(a order by b)(postgresql 9.0及之后才可用)方法,将轨迹点进行合并。 with f1 as(--依据车牌号分组,按时间递增排序并提取每个轨迹点在分组中的行号 select platenumber, lon, lat, extract...