SQL loop statements in several ways (variable loops, cursor loops, transactions)

-First

Declare @orderNum varchar(255)Create Table#ttableName (IDint Identity(1,1), Ordersvarchar(255))Declare @n int,@rows int

Insert#ttableName (Orders)SelectOrdernum fromForderswhereOrderId< ---Select @rows =count (1) from Pe_ordersSelect @rows =@ @rowcount Set @n=1  while @n<=@rows 　　 begin 　　　　 Select @orderNum=Ordernum fromPe_orderswhereOrdernum=(SelectOrders from#ttableNamewhereId=@n)Print(@OrderNum)Select @n=@n+1 　　 EndDrop Table#ttableName

-Second

Declare @tmp varchar( -)--temporary variable to hold the cursor valueDeclareY_currcursor  for --declare that the cursor is OrdernumSelectOrdernum fromForderswhereOrderId< -OpenY_curr--Open CursorFetch Next  fromY_curr into @tmp ----Start loop cursor variable while(@ @fetch_status=0)---Returns the state of the last cursor executed by the FETCH statement, rather than the state of any cursors currently open for the connection.  　　 begin 　　　　 Print(@tmp)UpdateFordersSetfunctionary+@tmp whereOrdernum=@tmp --manipulating Databases 　　　　 Fetch Next  fromY_curr into @tmp --start loop cursor variable 　　 EndCloseY_curr--Close CursorsdeallocateY_curr--Releasing Cursors

--Third

SelectOrdernum,username,moneytotal into#t fromforders PODECLARE @n int,@error int--Set @n=1Set @error=0 　　 BEGIN TRAN --Declaration of Business 　　　　 Declare @tmp varchar( -),@userN varchar( -)--temporary variable to hold the cursor value 　　　　 DeclareY_currcursor  for --declare that the cursor is Ordernum,username 　　　　 SelectOrdernum,username fromForderswhereOrderid< - 　　　　 OpenY_currFetch Next  fromY_curr into @tmp,@userN 　　　　  while @ @fetch_status = 0 　　　　　　 BEGIN 　　　　　　　　 Select IsNull(sum(Moneytotal),0), Ordernum from#twhereUsername=@userN 　　　　　　　　 --Set @[email protected]+1 　　　　　　　　 Set @error=@error+@ @error--log whether the correct 0 is correct after each run of SQL　　　　　　　　 Fetch Next  fromY_curr into @tmp,@userN 　　　　　　 END 　　　　 IF @error=0 　　　　 BEGIN 　　 Commit Tran --SubmitENDELSE 　　 BEGIN 　　　　 ROLLBACK TRAN --rolling back 　　 ENDCloseY_currdeallocateY_currDROP TABLE#t

SQL loop statements in several ways (variable loops, cursor loops, transactions)