select ProductSN,max(col1) col1,max(col2) col2,max(col3) col3,...
from tb
group by ProductSN

------解决方案--------------------
SQL code
create table tb(ProductSN varchar(120),Gain_min decimal(18,6), Gain_max decimal(18,6),VSWR_ANT_879 decimal(18,6),VSWR_Rx decimal(18,6),F_ANT_Rx_20 decimal(18,6), F_ANT_Rx_816 decimal(18,6))
go
insert into tb  
select 'A8319050032411501784',NULL, NULL ,NULL, NULL, NULL, NULL  union all
select 'A8319050032411501784',NULL,NULL, NULL, NULL ,NULL ,52.1600 union all
select 'A8319050032411501784',NULL, NULL, NULL ,NULL, 106.8700, NULL union all
select 'A8319050032411501784',NULL, NULL, NULL, 25.3600 ,NULL, NULL union all
select 'A8319050032411501784',NULL ,NULL ,23.3800, NULL, NULL, NULL union all
select 'A8319050032411501784',19.5200, 20.4100, NULL, NULL ,NULL, NULL
go
select ProductSN,max(Gain_min) Gain_min,max(Gain_max) Gain_max,max(VSWR_ANT_879) VSWR_ANT_879,max(VSWR_Rx) VSWR_Rx,max(F_ANT_Rx_20) F_ANT_Rx_20,max(F_ANT_Rx_816) F_ANT_Rx_816
from tb
group by ProductSN
/*
ProductSN    Gain_min    Gain_max    VSWR_ANT_879    VSWR_Rx    F_ANT_Rx_20    F_ANT_Rx_816
A8319050032411501784    19.520000    20.410000    23.380000    25.360000    106.870000    52.160000
*/