很久没用arcpy了,碰了好几次壁,把这次做的贴上来,以备下次可以跳过这些简单的问题 import arcpy arcpy.env.workspace = 'C:\Users\Qian\Documents\ArcGIS\Default.gdb' a=['sichuan1990','sichuan2000','sichuan2010'] b=['藏族','彝族','羌族','回族'] for x in a: for y in b: arcpy.MeanCenter_stats(x, x+y+"1.
例如以下情况,假如字段3是日期类型,按照小时分组统计字段1为空的个数,并对字段2大于5的值求和: SELECT SUM(CASE WHEN field1 IS NULL THEN 1 ELSE 0 END) AS field1count,SUM(CASE WHEN field2>5 then field2 else 0 end) AS field2sumGROUP BY CONVERT(VARCHAR(13),field3,120)
在sql中,如果有group by,那么select的字段只能包含分组内容,或者count.sum.avg这些统计字段. 但在linq里面,是:group 你想要什么字段 by 分组字段 比如: var q = from p in db.Products group p by p.CategoryID into g select g; 实际应用中,多表多字段参与分组比较常见: from a in TableA join b in TableB on a.Id equals b.aId || b.
想用ef来写一个统计字段的语句,如下所示 select sum(price) as price_total, sum(amount) as amount_total from table1 发现似乎实现不了,ef只能 dbContext.Table.Sum(e=>e.price);dbContext.Table.Sum(e=>e.amount)这样一个一个查,没办法一次查询多个聚合函数字段 经过我的研究后,我发现可以曲线救国. dbContext.). Select(g => new {