--測試數據
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

--缺號分布查詢
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 --為每組編號補充查詢起始編號是否缺號的輔助記錄
?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 --過濾掉每組數據中,編號最大的記錄
?AND NOT EXISTS(
??SELECT * FROM tb WHERE col1=a.col1 AND col2=a.col2+1)
ORDER BY a.col1,start_col2
/*--結果
col1?????? start_col2? end_col2???
-------------- -------------- -----------
a????????? 1?????????? 1
a????????? 4?????????? 5
b????????? 2?????????? 4
--*/

查詢缺號分布情況的示例.sql