5.4.2 查询缺号分布情况的示例.sql 
  
 --测试数据 
 CREATE TABLE tb(col1 varchar(10),col2 int) 
 INSERT tb SELECT 'a',2 
 UNION ALL SELECT 'a',3 
 UNION ALL SELECT 'a',6 
 UNION ALL SELECT 'a',7 
 UNION ALL SELECT 'a',8 
 UNION ALL SELECT 'b',1 
 UNION ALL SELECT 'b',5 
 UNION ALL SELECT 'b',6 
 UNION ALL SELECT 'b',7 
 GO 
  
 --缺号分布查询 
 SELECT a.col1,start_col2=a.col2+1, 
 	end_col2=( 
 		SELECT MIN(col2) FROM tb aa 
 		WHERE col1=a.col1 AND col2>a.col2  
 			AND NOT EXISTS( 
 				SELECT * FROM tb WHERE col1=aa.col1 AND col2=aa.col2-1)) 
 		-1 
 FROM( 
 	SELECT col1,col2 FROM tb 
 	UNION ALL --为每组编号补充查询起始编号是否缺号的辅助记录 
 	SELECT DISTINCT col1,0 FROM tb 
 )a,(SELECT col1,col2=MAX(col2) FROM tb GROUP BY col1)b 
 WHERE a.col1=b.col1 AND a.col2 <b.col2 --过滤掉每组数据中,编号最大的记录 
 	AND NOT EXISTS( 
 		SELECT * FROM tb WHERE col1=a.col1 AND col2=a.col2+1) 
 ORDER BY a.col1,start_col2 
 /*--结果 
 col1     start_col2  end_col2   
 -------------- -------------- -----------  
 a      1       1 
 a      4       5 
 b      2       4 
 --*/

--借用临时表：
create table tb(id int)
insert into tb select 1
insert into tb select 2
insert into tb select 3
insert into tb select 5
insert into tb select 6
insert into tb select 7
insert into tb select 9
insert into tb select 11
insert into tb select 12


declare @sql varchar(1000)
select @sql='select top '+cast(max(id) as varchar)+' bh=identity(int,1,1) into ## from syscolumns' from tb
exec(@sql)
select bh from ## where not exists(select 1 from tb where bh=id)