1.用一条语句得出某日期所在月份的最大天数？
SELECT DAY(DATEADD(dd, -1, DATEADD(mm, 1, DATEADD(dd, 1-DAY('2004-8-31'), '2004-8-31')))) AS 'Day Number'
2.少记录变成多条记录问题
有表tbl日期;;;;收入;支出2004-02-11 00:00:00 60 452004-03-01 00:00:00 60 452004-03-02 00:00:00 40 502004-03-05 00:00:00 50 40
/*测试数据：Create Table tbl([日期] smalldatetime,[收入] int ,[支出] int)
Insert Into tblSELECT '2004-02-11', 60, 45union SELECT '2004-03-01',60, 45union SELECT '2004-03-02',40, 50union SELECT '2004-03-05',50, 40*/
要得到的结果：日期收入; 支出; 余额; ------------------------------------------------------ ----------- ----------- ----------- 2004-02-01 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-02 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-03 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-04 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-05 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-06 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-07 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-08 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-09 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-10 00:00:00;NULL;;;;;NULL;;;;;NULL2004-02-11 00:00:00;60;45152004-02-12 00:00:00;NULL;;;;;NULL;;;;;152004-02-13 00:00:00;NULL;;;;;NULL;;;;;152004-02-14 00:00:00;NULL;;;;;NULL;;;;;152004-02-15 00:00:00;NULL;;;;;NULL;;;;;152004-02-16 00:00:00;NULL;;;;;NULL;;;;;152004-02-17 00:00:00;NULL;;;;;NULL;;;;;152004-02-18 00:00:00;NULL;;;;;NULL;;;;;152004-02-19 00:00:00;NULL;;;;;NULL;;;;;152004-02-20 00:00:00;NULL;;;;;NULL;;;;;152004-02-21 00:00:00;NULL;;;;;NULL;;;;;152004-02-22 00:00:00;NULL;;;;;NULL;;;;;152004-02-23 00:00:00;NULL;;;;;NULL;;;;;152004-02-24 00:00:00;NULL;;;;;NULL;;;;;152004-02-25 00:00:00;NULL;;;;;NULL;;;;;152004-02-26 00:00:00;NULL;;;;;NULL;;;;;152004-02-27 00:00:00;NULL;;;;;NULL;;;;;152004-02-28 00:00:00;NULL;;;;;NULL;;;;;152004-02-29 00:00:00;NULL;;;;;NULL;;;;;152004-03-01 00:00:00;60;45302004-03-02 00:00:00;40;50202004-03-03 00:00:00;NULL;;;;;NULL;;;;;202004-03-04 00:00:00;NULL;;;;;NULL;;;;;202004-03-05 00:00:00;50;40302004-03-06 00:00:00;NULL;;;;;NULL;;;;;302004-03-07 00:00:00;NULL;;;;;NULL;;;;;302004-03-08 00:00:00;NULL;;;;;NULL;;;;;302004-03-09 00:00:00;NULL;;;;;NULL;;;;;302004-03-10 00:00:00;NULL;;;;;NULL;;;;;302004-03-11 00:00:00;NULL;;;;;NULL;;;;;302004-03-12 00:00:00;NULL;;;;;NULL;;;;;302004-03-13 00:00:00;NULL;;;;;NULL;;;;;302004-03-14 00:00:00;NULL;;;;;NULL;;;;;302004-03-15 00:00:00;NULL;;;;;NULL;;;;;302004-03-16 00:00:00;NULL;;;;;NULL;;;;;302004-03-17 00:00:00;NULL;;;;;NULL;;;;;302004-03-18 00:00:00;NULL;;;;;NULL;;;;;302004-03-19 00:00:00;NULL;;;;;NULL;;;;;302004-03-20 00:00:00;NULL;;;;;NULL;;;;;302004-03-21 00:00:00;NULL;;;;;NULL;;;;;302004-03-22 00:00:00;NULL;;;;;NULL;;;;;302004-03-23 00:00:00;NULL;;;;;NULL;;;;;302004-03-24 00:00:00;NULL;;;;;NULL;;;;;302004-03-25 00:00:00;NULL;;;;;NULL;;;;;302004-03-26 00:00:00;NULL;;;;;NULL;;;;;302004-03-27 00:00:00;NULL;;;;;NULL;;;;;302004-03-28 00:00:00;NULL;;;;;NULL;;;;;302004-03-29 00:00:00;NULL;;;;;NULL;;;;;302004-03-30 00:00:00;NULL;;;;;NULL;;;;;302004-03-31 00:00:00;NULL;;;;;NULL;;;;;30
答案：
SELECT Y.[日期], tbl.[收入], tbl.[支出], ( SELECT SUM(ISNULL(tbl.[收入], 0)-ISNULL(tbl.[支出], 0)) FROM tbl WHERE [日期]<=Y.[日期]) AS [余额] FROM tbl RIGHT JOIN ( SELECT DATEADD(dd, N.i, DATEADD(dd, 1-DAY(m.MinDay), m.MinDay)) AS [日期] FROM ( SELECT 0 AS i UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9 UNION ALL SELECT 10 UNION ALL SELECT 11 UNION ALL SELECT 12 UNION ALL SELECT 13 UNION ALL SELECT 14 UNION ALL SELECT 15 UNION ALL SELECT 16 UNION ALL SELECT 17 UNION ALL SELECT 18 UNION ALL SELECT 19 UNION ALL SELECT 20 UNION ALL SELECT 21 UNION ALL SELECT 22 UNION ALL SELECT 23 UNION ALL SELECT 24 UNION ALL SELECT 25 UNION ALL SELECT 26 UNION ALL SELECT 27 UNION ALL SELECT 28 UNION ALL SELECT 29 UNION ALL SELECT 30 UNION ALL SELECT 31 ) N, ( SELECT MIN(日期) AS MinDay FROM tbl GROUP BY DATEDIFF(month, 0, 日期) ) M WHERE DATEDIFF(mm, DATEADD(dd, N.i, DATEADD(dd, 1-DAY(m.MinDay), m.MinDay)), M.MinDay)=0) AS Y ON tbl.[日期]=Y.日期
