假设我有以下简单的表变量:
declare @databases table
(
DatabaseID int,
Name varchar(15),
Server varchar(15)
)
-- insert a bunch rows into @databases
如果我想遍历各行,声明和使用游标是我唯一的选择吗?还有别的办法吗?
假设我有以下简单的表变量:
declare @databases table
(
DatabaseID int,
Name varchar(15),
Server varchar(15)
)
-- insert a bunch rows into @databases
如果我想遍历各行,声明和使用游标是我唯一的选择吗?还有别的办法吗?
当前回答
-- [PO_RollBackOnReject] 'FININV10532'
alter procedure PO_RollBackOnReject
@CaseID nvarchar(100)
AS
Begin
SELECT *
INTO #tmpTable
FROM PO_InvoiceItems where CaseID = @CaseID
Declare @Id int
Declare @PO_No int
Declare @Current_Balance Money
While (Select ROW_NUMBER() OVER(ORDER BY PO_LineNo DESC) From #tmpTable) > 0
Begin
Select Top 1 @Id = PO_LineNo, @Current_Balance = Current_Balance,
@PO_No = PO_No
From #Temp
update PO_Details
Set Current_Balance = Current_Balance + @Current_Balance,
Previous_App_Amount= Previous_App_Amount + @Current_Balance,
Is_Processed = 0
Where PO_LineNumber = @Id
AND PO_No = @PO_No
update PO_InvoiceItems
Set IsVisible = 0,
Is_Processed= 0
,Is_InProgress = 0 ,
Is_Active = 0
Where PO_LineNo = @Id
AND PO_No = @PO_No
End
End
其他回答
这将在SQL SERVER 2012版本中工作。
declare @Rowcount int
select @Rowcount=count(*) from AddressTable;
while( @Rowcount>0)
begin
select @Rowcount=@Rowcount-1;
SELECT * FROM AddressTable order by AddressId desc OFFSET @Rowcount ROWS FETCH NEXT 1 ROWS ONLY;
end
简单说明一下,如果你使用的是SQL Server(2008及以上版本),下面的例子有:
While (Select Count(*) From #Temp) > 0
会不会更好
While EXISTS(SELECT * From #Temp)
Count将不得不触及表中的每一行,EXISTS只需要触及第一行。
这是我使用的2008 R2代码。我使用的这段代码是在所有故事的关键字段(SSNO & EMPR_NO)上构建索引
if object_ID('tempdb..#a')is not NULL drop table #a
select 'IF EXISTS (SELECT name FROM sysindexes WHERE name ='+CHAR(39)+''+'IDX_'+COLUMN_NAME+'_'+SUBSTRING(table_name,5,len(table_name)-3)+char(39)+')'
+' begin DROP INDEX [IDX_'+COLUMN_NAME+'_'+SUBSTRING(table_name,5,len(table_name)-3)+'] ON '+table_schema+'.'+table_name+' END Create index IDX_'+COLUMN_NAME+'_'+SUBSTRING(table_name,5,len(table_name)-3)+ ' on '+ table_schema+'.'+table_name+' ('+COLUMN_NAME+') ' 'Field'
,ROW_NUMBER() over (order by table_NAMe) as 'ROWNMBR'
into #a
from INFORMATION_SCHEMA.COLUMNS
where (COLUMN_NAME like '%_SSNO_%' or COLUMN_NAME like'%_EMPR_NO_')
and TABLE_SCHEMA='dbo'
declare @loopcntr int
declare @ROW int
declare @String nvarchar(1000)
set @loopcntr=(select count(*) from #a)
set @ROW=1
while (@ROW <= @loopcntr)
begin
select top 1 @String=a.Field
from #A a
where a.ROWNMBR = @ROW
execute sp_executesql @String
set @ROW = @ROW + 1
end
我将提供基于集合的解决方案。
insert @databases (DatabaseID, Name, Server)
select DatabaseID, Name, Server
From ... (Use whatever query you would have used in the loop or cursor)
这比任何循环技术都要快得多,而且更容易编写和维护。
下面是我的解决方案,它使用了一个无限循环、BREAK语句和@@ROWCOUNT函数。没有游标或临时表是必要的,我只需要写一个查询,以获得下一行在@databases表:
declare @databases table
(
DatabaseID int,
[Name] varchar(15),
[Server] varchar(15)
);
-- Populate the [@databases] table with test data.
insert into @databases (DatabaseID, [Name], [Server])
select X.DatabaseID, X.[Name], X.[Server]
from (values
(1, 'Roger', 'ServerA'),
(5, 'Suzy', 'ServerB'),
(8675309, 'Jenny', 'TommyTutone')
) X (DatabaseID, [Name], [Server])
-- Create an infinite loop & ensure that a break condition is reached in the loop code.
declare @databaseId int;
while (1=1)
begin
-- Get the next database ID.
select top(1) @databaseId = DatabaseId
from @databases
where DatabaseId > isnull(@databaseId, 0);
-- If no rows were found by the preceding SQL query, you're done; exit the WHILE loop.
if (@@ROWCOUNT = 0) break;
-- Otherwise, do whatever you need to do with the current [@databases] table row here.
print 'Processing @databaseId #' + cast(@databaseId as varchar(50));
end