【SQL Server学习笔记】T-SQL中的流程控制、游标

1、流控制 

--一直到11:07:00才运行 --waitfor time '11:07:00'  declare @temp table(schematable varchar(100))  declare @tablename varchar(100)  insert into @temp (schematable) select s.name + '.' + t.name from sys.tables t inner join sys.schemas s         on t.schema_id = s.schema_id where t.type_desc = 'User_table'  --while循环结构 while (select COUNT(*) from @temp ) > 0 begin 	 	select top (1) @tablename = schematable 	from @temp 	 	exec sp_spaceused @tablename;  --输出当前数据库中每个表的空间使用情况 	 	delete from @temp 	where schematable = @tablename 	 	--if-else分支结构 	if( (select COUNT(*) from @temp)=0 ) 	begin 	     	    --延迟10秒 	    waitfor delay '00:00:10' 	     		exec sp_spaceused;         --输出当前数据库的空间使用情况         break;     end     else     begin         continue;     end end 

2、游标

set nocount on  declare @session_id smallint  --1.定义游标 declare session_cur cursor local                     --作用范围：局部游标(LOCAL,GLOBAL) forward_only              --滚动方式：向前(FORWARD_ONLY,SCROLL) fast_forward              --获取数据方式:快速向前(STATIC,KEYSET,DYNAMIC,FAST_FORWARD) read_only                 --只读 (READ_ONLY,SCROLL_LOCKS,OPTIMISTIC) for select session_id     from sys.dm_exec_requests     where status in ('runnable','sleeping','running')           and session_id >50  --2.打开游标 open session_cur  --3.取下一条 fetch next from session_cur  into @session_id  --4.开始循环 while @@FETCH_STATUS = 0 begin 	 	print 'spid #:' + str(@session_id); 	 	exec('dbcc outputbuffer(' + @session_id + ')') ; 	 	fetch next from session_cur 	into @session_id end  close session_cur       --5.关闭游标  deallocate session_cur  --6.释放游标占用的资源