partition的意思是对数据进行分区,sql语句如下 select * from ( SELECT ROW_NUMBER() over(partition by [姓名] order by [打卡时间] desc) as rowNum ,[姓名] ,[打卡时间] FROM [dbo].[打卡记录表] ) temp where temp.rowNum = 1 通过partition by [姓名] order by [打卡时间] desc,这句就可以做到,...
partition的意思是对数据进行分区,sql语句如下 1select*from2(3SELECT4ROW_NUMBER()over(partitionby[姓名]orderby[打卡时间]desc)asrowNum5,[姓名]6,[打卡时间]7FROM[dbo].[打卡记录表]8)temp9wheretemp.rowNum=1 通过partition by [姓名] order by [打卡时间] desc,这句就可以做到,让数据按照姓名分组,并且...
SELECT * FROM student WHERE id < 50; -- 删除分区中的数据 DELETE FROM student WHERE id < 50; -- 添加新分区 ALTER TABLE student ADD PARTITION ( PARTITION p4 VALUES LESS THAN (200) ); -- 删除分区 ALTER TABLE student DROP PARTITION p0; -- 检查分区信息 SHOW CREATE TABLE student; 1. 2...
因为窗口函数是对where或者group by子句处理后的结果进行操作,所以窗口函数原则上只能写在select子句中。 二、窗口函数使用 1、专用窗口函数rank 例1 查询班级表,要求每个班级内按成绩排名。 1)每个班级内按班级分组,partition by用来对表分组,这里指定了按“班级”分组(partition by 班级) 2)按成绩排名,order by子...
SELECT*FROM`my_partitioned_table`; 1. 使用SELECT语句查看插入的数据,确保数据已成功插入到分区表中。 4. 按分区查询数据 当数据量较大时,按分区查询可以提高查询性能。可以通过以下步骤按分区查询数据: 查询单个分区 SELECT*FROM`my_partitioned_table`PARTITION(p1); ...
例如,假设有一个表名为table_name,分为3个分区(partition1、partition2、partition3),可以使用以下语句实现跨分区查询: SELECT * FROM table_name PARTITION (partition1) UNION ALL SELECT * FROM table_name PARTITION (partition2) UNION ALL SELECT * FROM table_name PARTITION (partition3); 复制代码 这样...
select*from(selectcity,price,rank()over(partitionbycityorderbypricedesc)asrank,dense_rank()over(partitionbycityorderbypricedesc)asdense_rank,row_number()over(partitionbycityorderbypricedesc)asrow_numberfromdatetable)pwherep.rank<=2 聚合开窗函数 ...
select $PARTITION.partfunSale(SaleTime) as 分区编号,count(id) as 记录数 from Sale group by $PARTITION.partfunSale(SaleTime) 以上代码的运行结果如下图所示: 除了在插入数据时程序员不需要去考虑分区表的物理情况之外,就是连修改数据也不需要考虑。SQL Server会自动将记录从一个分区表移到另一个分区表中...
SQL PARTITION BY SELECT * FROM ( SELECT ROW_NUMBER() OVER( PARTITION BY vb.GoodsID ORDER BY vb.InventorySum DESC ) AS rowindex,InventorySum AS sum1 ,* FROM dbo.v_BatchGoodsInventory AS vb WHERE vb.InventoryStatus = 1 AND vb.InventorySum > 0 AND vb.Status = 1...
select segment_name,partition_name,segment_type,bytes/1024/1024"字节数(M)",tablespace_name from user_segments where segment_nameIN('RANGE_PART_TAB','NOR_TAB'); 二、分区表优势 引用Oracle官方文档的说法,https://docs.oracle.com/cd/B19306_01/server.102/b14220/partconc.htm#sthref2604: ...