I've got a SQL Server table with about 50,000 rows in it.我有一个SQL Server表,其中包含大约50,000行。I want to select about 5,000 of those rows at random.我想随机选择大约5,000行。I've thought of a complicated way, creating a temp
接下来,是定制开发的阶段,可能需要开发特定的函数来封装随机行选择逻辑。 RandomRowSelector+getRandomRows(int count) publicclassRandomRowSelector{publicList<SampleData>GetRandomRows(intcount){using(varcontext=newSampleDbContext()){returncontext.SampleData.OrderBy(r=>Guid.NewGuid()).Take(count).ToList(...
SELECTtop1[ActivityID] ,[CardNo] ,[Password] ,[State] ,[CreateTime] ,NEWID()asRandom FROM[TGBus_Card].[dbo].[Ka_Card]WhereActivityID=501AndState=0OrderByRandom Select[语句执行花费时间(毫秒)]=Datediff(ms,@d,Getdate()) 确实有所提高!!但太不明显了。。。 还有没有更好的办法?! 于是我又...
This trace flag isn't required starting with SQL Server 2016 (13.x), as minimal logging is turned on by default for indexed tables. In SQL Server 2016 (13.x), when the bulk load operation causes a new page to be allocated, all of the rows sequentially filling that new page are ...
select data_1.tid1,data_1.id from row_num as row_num inner join data_1 as data_1 on data_1.tid1 = row_num.tid2 最后轮到 POSTGRESQL , 但是这样做性能在大数据量上是一个问题。 select d.* from (select floor(random() * (max(id) - min(id))) as id from test_d) as ma ...
Declare @d DatetimeSet @d=getdate()SELECT top 1[ActivityID],[CardNo],[Password],[State],[CreateTime],NEWID() as RandomFROM [TGBus_Card].[dbo].[Ka_Card] WhereActivityID=501AndState=0Order By RandomSelect [语句执行花费时间(毫秒)]=Datediff(ms,@d,Getdate()) ...
SQL Server 資料指標支援包含書籤的 OLE DB Driver for SQL Server 資料列集。 DBPROP_CHANGEINSERTEDROWS R/W︰讀取/寫入 預設值:VARIANT_FALSE 描述:如果資料列集使用的是索引鍵集驅動資料指標,僅能將此屬性設定為 VARIANT_TRUE。 DBPROP_COLUMNRESTRICT R/W︰唯讀 預設值:VARIANT_FALSE 描述:當取用者...
The ports are referred to as random RPC ports. In these cases, RPC clients rely on the RPC endpoint mapper to tell them which dynamic ports were assigned to the server. For some RPC-based services, you can configure a specific port instead of letting RPC assign one dynamically. You can ...
The following example updates the VacationHours column by 25 percent for 10 random rows in the Employee table. SQL Copy USE AdventureWorks2022; GO UPDATE TOP (10) HumanResources.Employee SET VacationHours = VacationHours * 1.25 ; GO If you must use TOP to apply updates in a meaningful ...
Common table expressions can also be used with the SELECT, INSERT, UPDATE, and CREATE VIEW statements. For more information, seeWITH common_table_expression (Transact-SQL). TOP(expression)[ PERCENT ] Specifies the number or percent of random rows that will be deleted.expressioncan be either a...