计算客户每种商品最后一次订货与第二次订货之间的间隔日期是多少?
销售表:saletable (clientno:客户编号,goodsno商品编号,dhdate 订购日期)
销费周期表:Zqtable (zq_clientno:客户编号,zq_goodsno:商品编号,zq_zq:周期),请大家帮帮忙,看看怎么能高效计算出来,客户及业务单据量都比较大。先谢谢大家!
create table saletable (proofno nvarchar(14),clientno nvarchar(4),goodsno nvarchar(2),dhdate datetime)
create table Zqtable(zq_clientno nvarchar(4),zq_goodsno nvarchar(2),zq_zq integer)
insert into saletable(proofno,clientno,goodsno,dhdate )
select 'DH200703110001','0003','01','2007-03-11' union
select 'DH200703120002','0001','02','2007-03-12' union
select 'DH200703130003','0001','01','2007-03-13' union
select 'DH200703010004','0001','03','2007-03-01' union
select 'DH200703110001','0002','01','2007-02-11' union
select 'DH200703120005','0001','02','2007-03-12' union
select 'DH200703130003','0003','01','2007-02-13' union
select 'DH200703010004','0001','03','2007-03-01'